From 43d9d1eac9a65b07f5d9312e9b71f72e9b33151c Mon Sep 17 00:00:00 2001
From: vakrilov <alexander.vakrilov@telerik.com>
Date: Wed, 21 Jun 2017 14:19:25 +0300
Subject: [PATCH] Reworked fonts logic

---
 apps/app/ui-tests-app/font/all-fonts.ts     |  92 +++---
 tns-core-modules/ui/styling/font-common.ts  |   9 +-
 tns-core-modules/ui/styling/font.android.ts |  46 ++-
 tns-core-modules/ui/styling/font.ios.ts     | 301 ++++++--------------
 4 files changed, 167 insertions(+), 281 deletions(-)

diff --git a/apps/app/ui-tests-app/font/all-fonts.ts b/apps/app/ui-tests-app/font/all-fonts.ts
index e31c847f9..ddc855cbc 100644
--- a/apps/app/ui-tests-app/font/all-fonts.ts
+++ b/apps/app/ui-tests-app/font/all-fonts.ts
@@ -4,9 +4,10 @@ import { StackLayout } from "ui/layouts/stack-layout";
 import { ScrollView } from "ui/scroll-view";
 import { Label } from "ui/label";
 import { FontStyle, FontWeight } from "ui/enums";
-import typeUtils = require("utils/types");
+import * as typeUtils from "utils/types";
 import { Color } from "color";
-import * as font from "ui/styling/font";
+import * as utils from "utils/utils";
+import { isIOS } from "platform";
 
 const genericFontFamilies = [
     "system",
@@ -14,8 +15,8 @@ const genericFontFamilies = [
     "serif",
     "monospace",
 ];
-var fontFamilies = [];
-var fontNames = [];
+let fontFamilies = [];
+let fontNames = [];
 const embeddedFontNames = [
     "FontAwesome",
     "Pacifico",
@@ -37,34 +38,36 @@ const fontWeights = [
     FontWeight.black,
 ];
 
-var green = new Color("Green");
-var red = new Color("Red");
-var white = new Color("White");
-var black = new Color("Black");
+let green = new Color("Green");
+let red = new Color("Red");
+let white = new Color("White");
+let black = new Color("Black");
 
-var compareIgnoreCase = function (a, b) {
+let compareIgnoreCase = function (a, b) {
     return a.toLowerCase().localeCompare(b.toLowerCase());
 };
 
-if (font.ios) {
-    // for (var f = 0; f < embeddedFontNames.length; f++) {
-    //     font.ios.registerFont(`fonts/${embeddedFontNames[f]}.ttf`);
-    // }
+if (isIOS) {
+    const nsFontFamilies = utils.ios.getter(UIFont, UIFont.familyNames);
+    for (let i = 0; i < nsFontFamilies.count; i++) {
+        const family = nsFontFamilies.objectAtIndex(i);
+        fontFamilies.push(family)
 
-    var font_internal = <any>font;
-    font_internal.ensureSystemFontSets();
+        const nsFonts = UIFont.fontNamesForFamilyName(family);
+        for (let j = 0; j < nsFonts.count; j++) {
+            const font = nsFonts.objectAtIndex(j);
+            fontNames.push(font)
+        }
+    }
 
-    (<Set<string>>font_internal.systemFontFamilies).forEach(f => fontFamilies.push(f));
     fontFamilies = fontFamilies.sort(compareIgnoreCase);
-
-    (<Set<string>>font_internal.systemFonts).forEach(f => fontNames.push(f));
     fontNames = fontNames.sort(compareIgnoreCase);
 }
 
 export function onPageLoaded(args: NavigatedData) {
-    var page = <Page>args.object;
-    var scrollView = new ScrollView();
-    var stackLayout = new StackLayout();
+    let page = <Page>args.object;
+    let scrollView = new ScrollView();
+    let stackLayout = new StackLayout();
     generateLabels(stackLayout);
     scrollView.content = stackLayout;
     page.content = scrollView;
@@ -72,25 +75,24 @@ export function onPageLoaded(args: NavigatedData) {
 
 function generateLabels(layout: StackLayout) {
     layout.addChild(prepareTitle("Generic Font Families", 24));
-    for (var f = 0; f < genericFontFamilies.length; f++) {
+    for (let f = 0; f < genericFontFamilies.length; f++) {
         layout.addChild(prepareTitle(genericFontFamilies[f], 20));
-        for (var s = 0; s < fontStyles.length; s++) {
-            for (var w = 0; w < fontWeights.length; w++) {
-                var view = prepareLabel(genericFontFamilies[f], fontStyles[s], fontWeights[w]);
+        for (let s = 0; s < fontStyles.length; s++) {
+            for (let w = 0; w < fontWeights.length; w++) {
+                let view = prepareLabel(genericFontFamilies[f], fontStyles[s], fontWeights[w]);
                 layout.addChild(view);
             }
         }
     }
 
-    if (fontFamilies.length > 0)
-    {
+    if (fontFamilies.length > 0) {
         layout.addChild(prepareTitle("Font Families", 24));
     }
-    for (var f = 0; f < fontFamilies.length; f++) {
+    for (let f = 0; f < fontFamilies.length; f++) {
         layout.addChild(prepareTitle(fontFamilies[f], 20));
-        for (var s = 0; s < fontStyles.length; s++) {
-            for (var w = 0; w < fontWeights.length; w++) {
-                var view = prepareLabel(fontFamilies[f], fontStyles[s], fontWeights[w]);
+        for (let s = 0; s < fontStyles.length; s++) {
+            for (let w = 0; w < fontWeights.length; w++) {
+                let view = prepareLabel(fontFamilies[f], fontStyles[s], fontWeights[w]);
                 layout.addChild(view);
             }
         }
@@ -99,22 +101,22 @@ function generateLabels(layout: StackLayout) {
     if (fontNames.length > 0) {
         layout.addChild(prepareTitle("Phone Fonts", 24));
     }
-    for (var f = 0; f < fontNames.length; f++) {
-        var view = prepareLabel(fontNames[f], "normal", "normal");
+    for (let f = 0; f < fontNames.length; f++) {
+        let view = prepareLabel(fontNames[f], "normal", "normal");
         layout.addChild(view);
     }
 
     if (embeddedFontNames.length > 0) {
         layout.addChild(prepareTitle("Embedded Fonts", 24));
     }
-    for (var f = 0; f < embeddedFontNames.length; f++) {
-        var view = prepareLabel(embeddedFontNames[f], "normal", "normal");
+    for (let f = 0; f < embeddedFontNames.length; f++) {
+        let view = prepareLabel(embeddedFontNames[f], "normal", "normal");
         layout.addChild(view);
     }
 }
 
 function prepareTitle(text: string, fontSize: number) {
-    var title = new Label();
+    let title = new Label();
     title.text = text;
     title.height = 100;
     title.backgroundColor = black;
@@ -128,23 +130,23 @@ function prepareTitle(text: string, fontSize: number) {
 }
 
 function prepareLabel(fontFamily: string, fontStyle: string, fontWeight: string): View {
-    var label = new Label();
+    let label = new Label();
     label["font-family"] = fontFamily;
-    var fontFamilyCss = `font-family: ${fontFamily}; `;
-    var fontStyleCss = fontStyle !== FontStyle.normal ? `font-style: ${fontStyle}; ` : "";
-    var fontWeightCss = fontWeight !== FontWeight.normal ? `font-weight: ${fontWeight}; ` : "";
-    var css = `${fontFamilyCss}${fontStyleCss}${fontWeightCss}`;
-    label.text = `${typeUtils.getClass(label) } {${css}};`;
+    let fontFamilyCss = `font-family: ${fontFamily}; `;
+    let fontStyleCss = fontStyle !== FontStyle.normal ? `font-style: ${fontStyle}; ` : "";
+    let fontWeightCss = fontWeight !== FontWeight.normal ? `font-weight: ${fontWeight}; ` : "";
+    let css = `${fontFamilyCss}${fontStyleCss}${fontWeightCss}`;
+    label.text = `${typeUtils.getClass(label)} {${css}};`;
     label.textWrap = true;
     label.style.textAlignment = "left";
     label.borderWidth = 1;
     label.borderColor = black;
-    label.style.padding = "2"; 
+    label.style.padding = "2";
     label.setInlineStyle(css);
     label.on("loaded", args => {
-        var sender = <Label>args.object;
+        let sender = <Label>args.object;
         if (sender.ios) {
-            var uiFont = _getUIFont(label);
+            let uiFont = _getUIFont(label);
             sender.text += `\niOS Font: ${uiFont.fontName};`;
             if (genericFontFamilies.indexOf(fontFamily) !== -1) {
                 return;
diff --git a/tns-core-modules/ui/styling/font-common.ts b/tns-core-modules/ui/styling/font-common.ts
index 400c4406c..84ff95c39 100644
--- a/tns-core-modules/ui/styling/font-common.ts
+++ b/tns-core-modules/ui/styling/font-common.ts
@@ -39,8 +39,13 @@ export class Font implements definitios.Font {
     }
 
     get isBold(): boolean {
-        return this._fontWeight.toLowerCase() === enums.FontWeight.bold
-            || this._fontWeight.toLowerCase() === "700";
+        const val = this._fontWeight.toLowerCase();
+        
+        return val === enums.FontWeight.semiBold ||
+            val === enums.FontWeight.bold ||
+            val === "700" ||
+            val === enums.FontWeight.extraBold ||
+            val === enums.FontWeight.black;
     }
     set isBold(value: boolean) {
         throw new Error("isBold is read-only");
diff --git a/tns-core-modules/ui/styling/font.android.ts b/tns-core-modules/ui/styling/font.android.ts
index e55414d93..0467e78a9 100644
--- a/tns-core-modules/ui/styling/font.android.ts
+++ b/tns-core-modules/ui/styling/font.android.ts
@@ -64,16 +64,7 @@ export class Font extends common.Font {
 
     public getAndroidTypeface(): android.graphics.Typeface {
         if (!this._typeface) {
-            var fontStyle = 0;
-            if (this.isBold) {
-                fontStyle |= android.graphics.Typeface.BOLD;
-            }
-            if (this.isItalic) {
-                fontStyle |= android.graphics.Typeface.ITALIC;
-            }
-
-            var typeFace  = createTypeface(this);
-            this._typeface = android.graphics.Typeface.create(typeFace, fontStyle);
+            this._typeface = createTypeface(this);
         }
         return this._typeface;
     }
@@ -128,39 +119,46 @@ function loadFontFromFile(fontFamily: string): android.graphics.Typeface {
 }
 
 function createTypeface(font: Font): android.graphics.Typeface {
-    //http://stackoverflow.com/questions/19691530/valid-values-for-androidfontfamily-and-what-they-map-to
-    var fonts = common.parseFontFamily(font.fontFamily);
-    var result = null;
-    if (fonts.length === 0) {
-        return null;
+    let fontStyle = 0;
+    if (font.isBold) {
+        fontStyle |= android.graphics.Typeface.BOLD;
+    }
+    if (font.isItalic) {
+        fontStyle |= android.graphics.Typeface.ITALIC;
     }
 
-    for (var i = 0; i < fonts.length; i++) {
+    //http://stackoverflow.com/questions/19691530/valid-values-for-androidfontfamily-and-what-they-map-to
+    const fonts = common.parseFontFamily(font.fontFamily);
+    let result = null;
+    for (let i = 0; i < fonts.length && !result; i++) {
         switch (fonts[i].toLowerCase()) {
             case common.genericFontFamilies.serif:
-                result = android.graphics.Typeface.create("serif" + getFontWeightSuffix(font.fontWeight), 0);
+                result = android.graphics.Typeface.create("serif" + getFontWeightSuffix(font.fontWeight), fontStyle);
                 break;
 
             case common.genericFontFamilies.sansSerif:
             case common.genericFontFamilies.system:
-                result = android.graphics.Typeface.create("sans-serif" + getFontWeightSuffix(font.fontWeight), 0);
+                result = android.graphics.Typeface.create("sans-serif" + getFontWeightSuffix(font.fontWeight), fontStyle);
                 break;
 
             case common.genericFontFamilies.monospace:
-                result = android.graphics.Typeface.create("monospace" + getFontWeightSuffix(font.fontWeight), 0);
+                result = android.graphics.Typeface.create("monospace" + getFontWeightSuffix(font.fontWeight), fontStyle);
                 break;
 
             default:
                 result = loadFontFromFile(fonts[i]);
+                if (fontStyle) {
+                    result = android.graphics.Typeface.create(result, fontStyle);
+                }
                 break;
         }
-
-        if (result) {
-            return result;
-        }
     }
 
-    return null;
+    if (fontStyle && !result) {
+        result = android.graphics.Typeface.create("sans-serif" + getFontWeightSuffix(font.fontWeight), fontStyle);
+    }
+
+    return result;
 }
 
 function getFontWeightSuffix(fontWeight: string): string {
diff --git a/tns-core-modules/ui/styling/font.ios.ts b/tns-core-modules/ui/styling/font.ios.ts
index 649840def..4f0d66928 100644
--- a/tns-core-modules/ui/styling/font.ios.ts
+++ b/tns-core-modules/ui/styling/font.ios.ts
@@ -2,8 +2,14 @@
 import common = require("./font-common");
 import fs = require("file-system");
 import * as traceModule from "trace";
-
 import * as utils from "utils/utils";
+import { device } from "platform"
+
+const EMULATE_OBLIQUE = true;
+const OBLIQUE_TRANSFORM = CGAffineTransformMake(1, 0, 0.2, 1, 0, 0);
+const DEFAULT_SERIF = "Times New Roman";
+const DEFAULT_MONOSPACE = "Courier New";
+const SUPPORT_FONT_WEIGHTS = parseFloat(device.osVersion) >= 10.0;
 
 export class Font extends common.Font {
     public static default = new Font(undefined, undefined, enums.FontStyle.normal, enums.FontWeight.normal);
@@ -38,160 +44,18 @@ export class Font extends common.Font {
     }
 }
 
-var areSystemFontSetsValid: boolean = false;
-export var systemFontFamilies = new Set<string>();
-export var systemFonts = new Set<string>();
-
-export function ensureSystemFontSets() {
-    if (areSystemFontSetsValid) {
-        return;
-    }
-
-    var nsFontFamilies = utils.ios.getter(UIFont, UIFont.familyNames);
-    for (var i = 0; i < nsFontFamilies.count; i++) {
-        var family = nsFontFamilies.objectAtIndex(i);
-        systemFontFamilies.add(family);
-
-        var nsFonts = UIFont.fontNamesForFamilyName(family);
-        for (var j = 0; j < nsFonts.count; j++) {
-            var font = nsFonts.objectAtIndex(j);
-            systemFonts.add(font);
-        }
-    }
-    areSystemFontSetsValid = true;
+function shouldUseSystemFont(fontFamily: string) {
+    return !fontFamily ||
+        fontFamily === common.genericFontFamilies.sansSerif ||
+        fontFamily === common.genericFontFamilies.system;
 }
 
-const DEFAULT_SERIF = "Times New Roman";
-const DEFAULT_MONOSPACE = "Courier New";
-
-function getFontFamilyRespectingGenericFonts(fontFamily: string): string {
-    if (!fontFamily) {
-        return fontFamily;
-    }
-
-    switch (fontFamily.toLowerCase()) {
-        case common.genericFontFamilies.serif:
-            return DEFAULT_SERIF;
-
-        case common.genericFontFamilies.monospace:
-            return DEFAULT_MONOSPACE;
-
-        default:
-            return fontFamily;
-    }
-}
-
-function createUIFont(font: Font, defaultFont: UIFont) {
-    var size = font.fontSize || defaultFont.pointSize;
-    var descriptor: UIFontDescriptor;
-
-    var symbolicTraits: number = 0;
-    if (font.isBold) {
-        symbolicTraits |= UIFontDescriptorSymbolicTraits.TraitBold;
-    }
-    if (font.isItalic) {
-        symbolicTraits |= UIFontDescriptorSymbolicTraits.TraitItalic;
-    }
-
-    descriptor = tryResolveWithSystemFont(font, size, symbolicTraits);
-
-    if (!descriptor) {
-        descriptor = tryResolveByFamily(font);
-    }
-
-    if (!descriptor) {
-        descriptor = utils.ios.getter(defaultFont, defaultFont.fontDescriptor).fontDescriptorWithSymbolicTraits(symbolicTraits);
-    }
-
-    return UIFont.fontWithDescriptorSize(descriptor, size);
-}
-
-function tryResolveWithSystemFont(font: Font, size: number, symbolicTraits: number): UIFontDescriptor {
-    var systemFont: UIFont;
-    switch (font.fontFamily) {
-        case common.genericFontFamilies.sansSerif:
-        case common.genericFontFamilies.system:
-            if ((<any>UIFont).systemFontOfSizeWeight) {// This method is available on iOS 8.2 and later.
-                systemFont = (<any>UIFont).systemFontOfSizeWeight(size, getiOSFontWeight(font.fontWeight));
-            }
-            else {
-                systemFont = UIFont.systemFontOfSize(size);
-            }
-            result = utils.ios.getter(systemFont, systemFont.fontDescriptor).fontDescriptorWithSymbolicTraits(symbolicTraits);
-            break;
-
-        case common.genericFontFamilies.monospace:
-            if ((<any>UIFont).monospacedDigitSystemFontOfSizeWeight) {// This method is available on iOS 9.0 and later.
-                systemFont = (<any>UIFont).monospacedDigitSystemFontOfSizeWeight(size, getiOSFontWeight(font.fontWeight));
-                result = utils.ios.getter(systemFont, systemFont.fontDescriptor).fontDescriptorWithSymbolicTraits(symbolicTraits);
-            }
-            break;
-    }
-
-    if (systemFont) {
-        var result = utils.ios.getter(systemFont, systemFont.fontDescriptor).fontDescriptorWithSymbolicTraits(symbolicTraits);
-        return result;
-    }
-
-    return null;
-}
-
-function tryResolveByFamily(font: Font): UIFontDescriptor {
-    var fonts = common.parseFontFamily(font.fontFamily);
-    var result: UIFontDescriptor = null;
-    if (fonts.length === 0) {
-        return null;
-    }
-
-    ensureSystemFontSets();
-
-    for (var i = 0; i < fonts.length; i++) {
-        var fontFamily = getFontFamilyRespectingGenericFonts(fonts[i]);
-        var fontFace = getiOSFontFace(fontFamily, font.fontWeight, font.isItalic);
-        if (systemFonts.has(fontFamily) && !fontFace) { // This is an actual font like `HelveticaNeue-UltraLightItalic` - don't apply font face attribute
-            result = UIFontDescriptor.fontDescriptorWithNameSize(fontFamily, 0);
-        }
-        else if (systemFontFamilies.has(fontFamily)) { // This is a font family like `Helvetica Neue` - apply font face attribute
-            result = createFontDescriptor(fontFamily, fontFace);
-        }
-
-        if (result) {
-            return result;
-        }
-    }
-
-    return null;
-}
-
-function createFontDescriptor(fontFamily: string, fontFace: string): UIFontDescriptor  {
-    var fontAttributes = NSMutableDictionary.alloc<string, any>().init();
-    fontAttributes.setObjectForKey(fontFamily, "NSFontFamilyAttribute");
-    if (fontFace) {
-        fontAttributes.setObjectForKey(fontFace, "NSFontFaceAttribute");
-    }
-    return UIFontDescriptor.fontDescriptorWithFontAttributes(fontAttributes);
-}
-
-// Available in iOS 8.2 and later. 
-declare var UIFontWeightThin: number;       //0.8
-declare var UIFontWeightUltraLight: number; //0.6
-declare var UIFontWeightLight: number;      //0.4
-declare var UIFontWeightRegular: number;    //0
-declare var UIFontWeightMedium: number;     //0.23
-declare var UIFontWeightSemibold: number;   //0.3
-declare var UIFontWeightBold: number;       //0.4
-declare var UIFontWeightHeavy: number;      //0.56
-declare var UIFontWeightBlack: number;      //0.62
-function getiOSFontWeight(fontWeight: string): number {
-    if (!(<any>UIFont).systemFontOfSizeWeight) {
-        throw new Error("Font weight is available in iOS 8.2 and later.");
-    }
-
+function getNativeFontWeight(fontWeight: string): number {
     switch (fontWeight) {
         case enums.FontWeight.thin:
-            return UIFontWeightThin;
-        case enums.FontWeight.extraLight:
             return UIFontWeightUltraLight;
+        case enums.FontWeight.extraLight:
+            return UIFontWeightThin;
         case enums.FontWeight.light:
             return UIFontWeightLight;
         case enums.FontWeight.normal:
@@ -215,76 +79,95 @@ function getiOSFontWeight(fontWeight: string): number {
     }
 }
 
-function combineWeightStringWithItalic(weight: string, isItalic: boolean) {
-    if (!isItalic) {
-        return weight;
+function getFontFamilyRespectingGenericFonts(fontFamily: string): string {
+    if (!fontFamily) {
+        return fontFamily;
     }
 
-    if (!weight) {
-        return "Italic";
+    switch (fontFamily.toLowerCase()) {
+        case common.genericFontFamilies.serif:
+            return DEFAULT_SERIF;
+
+        case common.genericFontFamilies.monospace:
+            return DEFAULT_MONOSPACE;
+
+        default:
+            return fontFamily;
+    }
+}
+
+function getSystemFont(size: number, nativeWeight: number, italic: boolean, symbolicTraits: number): UIFont {
+    let result = UIFont.systemFontOfSizeWeight(size, nativeWeight);
+    if (italic) {
+        let descriptor = utils.ios.getter(result, result.fontDescriptor).fontDescriptorWithSymbolicTraits(symbolicTraits);
+        result = UIFont.fontWithDescriptorSize(descriptor, size);
     }
 
-    return weight + " Italic";
+    return result;
 }
 
-function canLoadFont(fontFamily: string, fontFace: string) {
-    var trialDescriptor = createFontDescriptor(fontFamily, fontFace);
-    var trialFont = UIFont.fontWithDescriptorSize(trialDescriptor, 0);
-    return trialFont.familyName === fontFamily;
-}
+function createUIFont(font: Font, defaultFont: UIFont): UIFont {
+    let result: UIFont;
+    const size = font.fontSize || defaultFont.pointSize;
+    const nativeWeight = getNativeFontWeight(font.fontWeight);
+    const fontFamilies = common.parseFontFamily(font.fontFamily);
 
-function findCorrectWeightString(fontFamily: string, weightStringAlternatives: Array<string>, isItalic: boolean) {
-    var i = 0;
-    let length = weightStringAlternatives.length;
-    for (; i < length; i++) {
-        var possibleFontFace = combineWeightStringWithItalic(weightStringAlternatives[i], isItalic);
-        if (canLoadFont(fontFamily, possibleFontFace)) {
-            return weightStringAlternatives[i];
+    let symbolicTraits: number = 0;
+    if (font.isBold) {
+        symbolicTraits |= UIFontDescriptorSymbolicTraits.TraitBold;
+    }
+    if (font.isItalic) {
+        symbolicTraits |= UIFontDescriptorSymbolicTraits.TraitItalic;
+    }
+
+    let fontDescriptorTraits = {
+        [UIFontSymbolicTrait]: symbolicTraits
+    };
+
+    // IOS versions below 10 will not return the correct font when UIFontWeightTrait is set
+    // In this case - rely on UIFontSymbolicTrait only
+    if (SUPPORT_FONT_WEIGHTS) {
+        fontDescriptorTraits[UIFontWeightTrait] = nativeWeight;
+    }
+
+    for (let i = 0; i < fontFamilies.length; i++) {
+        const fontFamily = getFontFamilyRespectingGenericFonts(fontFamilies[i]);
+
+        if (shouldUseSystemFont(fontFamily)) {
+            result = getSystemFont(size, nativeWeight, font.isItalic, symbolicTraits);
+            break;
+        } else {
+            const fontAttributes = {
+                [UIFontDescriptorFamilyAttribute]: fontFamily,
+                [UIFontDescriptorTraitsAttribute]: fontDescriptorTraits
+            };
+
+            let descriptor = UIFontDescriptor.fontDescriptorWithFontAttributes(<any>fontAttributes);
+            result = UIFont.fontWithDescriptorSize(descriptor, size);
+
+            let actualItalic = utils.ios.getter(result, result.fontDescriptor).symbolicTraits & UIFontDescriptorSymbolicTraits.TraitItalic;
+            if (font.isItalic && !actualItalic && EMULATE_OBLIQUE) {
+                // The font we got is not actually italic so emulate that with a matrix
+                descriptor = descriptor.fontDescriptorWithMatrix(OBLIQUE_TRANSFORM);
+                result = UIFont.fontWithDescriptorSize(descriptor, size);
+            }
+
+            // Check if the resolved font has the correct font-family
+            // If not - fallback to the next font-family
+            if (result.familyName === fontFamily) {
+                break;
+            } else {
+                result = null;
+            }
         }
     }
-    return weightStringAlternatives[0];
-} 
 
-function getiOSFontFace(fontFamily: string, fontWeight: string, isItalic: boolean): string {
-    // ... with a lot of fuzzy logic and artificial intelligence thanks to the lack of font naming standards.
-    var weight: string;
-    switch (fontWeight) {
-        case enums.FontWeight.thin:
-            weight = "Thin";
-            break;
-        case enums.FontWeight.extraLight:
-            weight = findCorrectWeightString(fontFamily, ["Ultra Light", "UltraLight", "Extra Light", "ExtraLight", "Ultra light", "Ultralight", "Extra light", "Extralight"], isItalic);
-            break;
-        case enums.FontWeight.light:
-            weight = "Light";
-            break;
-        case enums.FontWeight.normal:
-        case "400":
-        case undefined:
-        case null:
-            weight = ""; // We dont' need to write Regular
-            break;
-        case enums.FontWeight.medium:
-            weight = "Medium";
-            break;
-        case enums.FontWeight.semiBold:
-            weight = findCorrectWeightString(fontFamily, ["Demi Bold", "DemiBold", "Semi Bold", "SemiBold", "Demi bold", "Demibold", "Semi bold", "Semibold"], isItalic);
-            break;
-        case enums.FontWeight.bold:
-        case "700":
-            weight = "Bold";
-            break;
-        case enums.FontWeight.extraBold:
-            weight = findCorrectWeightString(fontFamily, ["Heavy", "Extra Bold", "ExtraBold", "Extra bold", "Extrabold"], isItalic);
-            break;
-        case enums.FontWeight.black:
-            weight = "Black";
-            break;
-        default:
-            throw new Error(`Invalid font weight: "${fontWeight}"`);
+    // Couldn't resolve font - fallback to the system font
+    if (!result) {
+        result = getSystemFont(size, nativeWeight, font.isItalic, symbolicTraits);
     }
 
-    return combineWeightStringWithItalic(weight, isItalic);
+    return result;
 }
 
 export module ios {
@@ -312,8 +195,6 @@ export module ios {
                 trace.write("Error occur while registering font: " + CFErrorCopyDescription(<NSError>error.value), trace.categories.Error, trace.messageType.error);
             }
         }
-
-        areSystemFontSetsValid = false;
     }
 }