feat(ios): fire onDisplayed event when first frame is ready to be displayed (#5344)

* feat: add a 'profiling: lifecycle' to track startup times

* feat: log when displayed event fires

* feat(ios): fire onDisplayed event when first frame is ready to be
displayed

tns-core-modules/profiling/profiling.d.ts

@@ -11,10 +11,25 @@ interface TimerInfo {
 
 /**
  * Profiling mode to use.
- *  - `counters` Accumulates method call counts and times until dumpProfiles is called and then prints agregated statistic in the console. This is the default.
+ *  - `counters` Accumulates method call counts and times until dumpProfiles is called and then prints aggregated statistic in the console. This is the default.
  *  - `timeline` Outputs method names along start/end timestamps in the console on the go.
+ *  - `lifecycle` Outputs basic non-verbose times for startup, navigation, etc.
  */
-type InstrumentationMode = "counters" | "timeline";
+type InstrumentationMode = "counters" | "timeline" | "lifecycle";
+
+/**
+ * Logging levels in order of verbosity.
+ */
+export enum Level {
+    none,
+    lifecycle,
+    timeline,
+}
+
+/**
+ * Get the current logging level.
+ */
+export function level(): Level;
 
 /**
  * Enables profiling.
@@ -32,8 +47,9 @@ type InstrumentationMode = "counters" | "timeline";
  * ```
  * 
  * @param type Profiling mode to use.
- *  - "counters" - Accumulates method call counts and times until dumpProfiles is called and then prints agregated statistic in the console. This is the default.
+ *  - "counters" - Accumulates method call counts and times until dumpProfiles is called and then prints aggregated statistic in the console. This is the default.
  *  - "timeline" - Outputs method names along start/end timestamps in the console on the go.
+ *  - "lifecycle" - Outputs basic non-verbose times for startup, navigation, etc.
  */
 export declare function enable(type?: InstrumentationMode): void;
 
@@ -132,4 +148,14 @@ export function uptime(): number;
 /**
  * Logs important messages. Contrary to console.log's behavior, the profiling log should output even for release builds.
  */
-export function log(message: string): void;
+export function log(message: string): void;
+
+/**
+ * Manually output profiling messages. The `@profile` decorator is useful when measuring times that function calls take on the stack
+ * but when measuring times between longer periods (startup times, times between the navigatingTo - navigatedTo events etc.)
+ * you can call this method and provide manually the times to be logged.
+ * @param message A string message
+ * @param start The start time (see `time()`)
+ * @param end The end time (see `time()`)
+ */
+export function trace(message: string, start: number, end: number): void;

tns-core-modules/profiling/profiling.ts

@@ -10,9 +10,8 @@ export function uptime() {
 export function log(message: string): void {
     if ((<any>global).__nslog) {
         (<any>global).__nslog("CONSOLE LOG: " + message);
-    } else {
-        console.log(message);
     }
+    console.log(message);
 }
 
 interface TimerInfo extends TimerInfoDefinition {
@@ -130,12 +129,24 @@ const enum MemberType {
     Instance
 }
 
+export enum Level {
+    none,
+    lifecycle,
+    timeline,
+}
+let tracingLevel: Level = Level.none;
+
 let profileFunctionFactory: <F extends Function>(fn: F, name: string, type?: MemberType) => F;
 export function enable(mode: InstrumentationMode = "counters") {
     profileFunctionFactory = mode && {
         counters: countersProfileFunctionFactory,
         timeline: timelineProfileFunctionFactory
     }[mode];
+
+    tracingLevel = {
+        lifecycle: Level.lifecycle,
+        timeline: Level.timeline,
+    }[mode] || Level.none;
 }
 
 try {
@@ -294,3 +305,11 @@ export function stopCPUProfile(name: string) {
         __stopCPUProfiler(name);
     }
 }
+
+export function level(): Level {
+    return tracingLevel;
+}
+
+export function trace(message: string, start: number, end: number): void {
+    log(`Timeline: Modules: ${message}  (${start}ms. - ${end}ms.)`);
+}