Add documentation for How to handle crashes on startup

docs/HowTo-Handle-Crashes-On-Startup-template.md

@@ -0,0 +1,67 @@
+Introduction
+============
+
+To catch and send crashes that occur while the app is starting up, the app has to get adjusted a little bit to make this work.
+
+The challenges in this scenario are:
+
+- Sending crash reports needs to be asynchronous, otherwise it would block the main thread or bad network conditions could make it even worse
+- If the startup takes too long or the main thread is blocking too long, the watchdog process will kill the app
+- The app might crash again before the crash report could have been send
+
+
+HowTo
+=====
+
+1. Setup the SDK
+2. Check if the app crashed in the last session by checking `[BITCrashManager didCrashInLastSession]`
+3. Check if `[BITCrashManager timeintervalCrashInLastSessionOccured]` is below a treshhold that you define. E.g. say your app usually requires 2 seconds for startup, and giving sending a crash report some time, you mighe choose `5` seconds as the treshhold
+4. If the crash happened in that timeframe, delay your app initialization and show an intermediate screen
+5. Implement the `BITCrashManagerDelegate` protocol methods `- (void)crashManager:(BITCrashManager *)crashManager didFailWithError:(NSError *)error;` and `- (void)crashManagerDidFinishSendingCrashReport:(BITCrashManager *)crashManager;` and continue app initialization
+
+Example
+=======
+
+	@interface BITAppDelegate () <BITCrashManagerDelegate> {}
+	@end
+	
+	
+	@implementation BITAppDelegate
+	
+	- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
+	  [self.window makeKeyAndVisible];
+	
+	  [[BITHockeyManager sharedHockeyManager] configureWithIdentifier:@"<>"
+	                                                         delegate:nil];
+	  
+	  // optionally enable logging to get more information about states.
+	  [BITHockeyManager sharedHockeyManager].debugLogEnabled = YES;
+	
+	  [[BITHockeyManager sharedHockeyManager] startManager];
+	  
+	  if ([[BITHockeyManager.crashmanager] didCrashInLastSession] &&
+	  	[[BITHockeyManager.crashmanager] timeintervalCrashInLastSessionOccured] < 5) {
+	  	// show intermediate UI
+	  } else {
+	  	[self setupApplication];
+	  }
+	  
+	  return YES;
+	}
+	
+	- (void)setupApplication {
+	  // setup your app specific code
+	}
+	
+	#pragma mark - BITCrashManagerDelegate
+	
+	- (void)crashManager:(BITCrashManager *)crashManager didFailWithError:(NSError *)error {
+	  [self setupApplication];
+	}
+	
+	- (void)crashManagerDidFinishSendingCrashReport:(BITCrashManager *)crashManager {
+	 [self setupApplication];
+	}
+	
+	@end
+

docs/index.md

@@ -29,6 +29,7 @@ HowTos
 
 - [How to do app versioning](HowTo-App-Versioning)
 - [How to upload symbols for crash reporting](HowTo-Upload-Symbols)
+- [How to handle crashes on startup](HowTo-Handle-Crashes-On-Startup)
 
 Troubleshooting
 ===============