waiting on a locked NSLock until tryLock succeeds

I have a class with 2 methods, the first one makes an animation for a second and the second performs some task.

This class is being called from a second class to perform those two operations consecutively but I want to enforce a lock so that the second operation runs only when the first one finished.

My Question is, what is the best way to do that.

here is my code:

@implementation Server


- (id)init{

    if ( (self = [super init]) ) {
        syncLock = [[NSLock alloc] init];
    }
    return self;
}

- (void)operationA {
    NSLog(@"op A started");

    [syncLock lock];

    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(50, 50, 50, 50)];
    [view setBackgroundColor:[UIColor redColor]];
    [[[[UIApplication sharedApplication] delegate] window] addSubview:view];

    [UIView beginAnimations:@"opA" context:nil];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(animationFinished)];
    [UIView setAnimationDuration:1.5f];
    [view setFrame:CGRectMake(50, 50, 150, 150)];
    [UIView commitAnimations];

}
- (void)animationFinished {
    [syncLock unlock];
    NSLog(@"Op A finished");

}

- (void)operationB {
    if ( ![syncLock tryLock]) {
        [[NSRunLoop cu开发者_运维知识库rrentRunLoop] addTimer:[NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(operationB) userInfo:nil repeats:NO] forMode:NSDefaultRunLoopMode];
        return;
    }
    NSLog(@"op B started");

    NSLog(@"perform some task here");
    [syncLock unlock];
    NSLog(@"op B finished");
}
@end

And the code that calls it:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

    // Override point for customization after application launch.

    [self.window makeKeyAndVisible];

    Server *server = [[Server alloc] init];
    [server operationA];
    [server operationB];

    return YES;
}

Option 1

Change operation A to be a BOOL method and return YES once completed and in your AppController

if([server operationA]) // operation A returns YES when completed so run operationB
    [server operationB];

Option 2 added as per JeremyP's comment

in your delegate method (animationFinished:) for OperationA add [self operationB]; to run operationB: at the end of your animation cycle.