Completion Blocks with BOOL and Return Type

	.h = - (void)signInAccountWithUserName:(NSString *)userName
	password:(NSString *)password
	completion:(void (^)(BOOL success))completionBlock;
	.m = - (void)signInAccountWithUserName:(NSString *)userName
	password:(NSString *)password
	completion:(void (^)(BOOL success))completionBlock
	{
	// Notice that we are passing a BOOL back to the completion block.
	if (completionBlock != nil) completionBlock(loginSuccessful);
	}
	//Call the method:
	[self signInAccountWithUserName:@"Bob"
	password:@"BobsPassword"
	completion:^{
	[self doMethod]; //do something like call a method
	}];
	OR
	[self signInAccountWithUserName:@"Bob"
	password:@"BobsPassword"
	completion:^(BOOL success) {
	if (success) {
	[self doMethod]; //do something like call a method
	} else {
	// do something like display an alert
	}
	}];

view raw CompletionBlocksWithBOOL.m hosted with ❤ by GitHub

	//Block that passes in an MKMapView and returns NSData called mapData
	.h = - (void)ImageFromMapView:(MKMapView*)mapView completion:(void (^)(NSData* mapData))completionBlock;
	.m = - (void)ImageFromMapView:(MKMapView*)mapView completion:(void (^)(NSData* mapData))completionBlock
	{
	//method does what it needs to do
	//self.data holds the NSData that was created inside this method
	completionBlock(self.data);
	}
	Calling it =
	[classWithMethod ImageFromMapView:mapView completion:^(NSData *mapData) {
	//do something with mapData
	}];

view raw CompletionBlocksWithReturn.m hosted with ❤ by GitHub