Allowing one method call at a time to a category method ios (@synchronized)

Question

I have a UIViewController and a Category for adding methods to the UIViewController. There is a method in the category:

@implementation UIViewController (AlertAnimationsAndModalViews)
-(void)someAddedMethod
{
    UIView *someView;
    //do some animation with the view that lasts 3 seconds
    //remove the view and return

}

And in any view controller i can call this method

[self someAddedMethod];

However, i only want to allow this method to run one at a time. For example, if i make two calls one after the other

[self someAddedMethod];//call1
[self someAddedMethod];//call2

i want the second call to wait until the first call has completed. I understand that UIView animationWithduration... is run in a seperate thread, and seeing as i cant create iVars in the category i cant really use @synchronized(someObject)..

Any advice?

Thanks in advance!

EDIT

The method looks like this:

 -(void)showTopBannerWithHeight:(CGFloat)height andWidth:(CGFloat)width andMessage:(NSString *)message andDuration:(CGFloat)duration
 {
 
 UILabel *messageLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, -height, width, height)];
[self.view.superview addSubview:messageLabel];


[UIView animateWithDuration:0.5
                      delay:0
                    options: UIViewAnimationOptionBeginFromCurrentState
                 animations:^{
                     messageLabel.frame = CGRectMake(0, 0, SCREEN_WIDTH, height);
                 }
                 completion:^(BOOL finished){
                     
                     [UIView animateWithDuration: 0.5
                                           delay:duration
                                         options: UIViewAnimationOptionBeginFromCurrentState
                                      animations:^{
                                          messageLabel.frame = CGRectMake(0, -height, SCREEN_WIDTH, height);
                                      }
                                      completion:^(BOOL finished){
                                          [messageLabel removeFromSuperview];
                                      }];
                 }];

}

So i show a "banner" from the top of the screen, wait for a duration (CGFloat) then slide the view out of the screen and remove. As this is in a category i can't add instance variables.. so what i want to achieve is that if more than one call to this method is made, i want the first call to execute without waiting, but each call after that to wait until the previous call has finished.

Answer 1

If its just about the animations you may check if ([someView.layer animationForKey:@"sameKeyAsOnCreation"] == nil). Than you will only add an animation, if it is not currently runnning.

You could also use associated objects to store the state on your own (animation running / not running).

Answer 2

Assuming you want to start next animation after previous one has finished. This way you can use some shared NSMutableArray* _animationQueue storage:

-(void)someAddedMethod
{
    NSTimeInterval duration = 3.0;

    void (^animationBlock)() = ^{
        //do some animations here 
        self.view.frame = CGRectOffset(self.view.frame, 40, 0);
    };

    __block void (^completionBlock)(BOOL) = ^(BOOL finished){
        [_animationQueue removeObjectAtIndex:0];
        if([_animationQueue count]>0) {
            [UIView animateWithDuration:duration animations:_animationQueue[0] completion:completionBlock];
        }
    };

    [_animationQueue addObject:animationBlock];
    if([_animationQueue count]==1) {
        [UIView animateWithDuration:duration animations:animationBlock completion:completionBlock];
    }
}

Note, you don't need any @synchronized features since everything goes on main thread.

UPDATE: the code below does exactly you need:

-(void)showTopBannerWithHeight:(CGFloat)height andWidth:(CGFloat)width andMessage:(NSString *)message andDuration:(CGFloat)duration
{
    static NSMutableArray* animationQueue = nil;
    if(!animationQueue) {
        animationQueue = [[NSMutableArray alloc] init];
    }

    void (^showMessageBlock)() = ^{
        UILabel *messageLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, width, height)];
        messageLabel.text = message;
        [self.view.superview addSubview:messageLabel];

        [UIView animateWithDuration: 0.5
                              delay:duration
                            options:UIViewAnimationOptionBeginFromCurrentState
                         animations:^{
                             messageLabel.frame = CGRectOffset(messageLabel.frame, 0, -height);
                         }
                         completion:^(BOOL finished){
                             [messageLabel removeFromSuperview];
                             [animationQueue removeObjectAtIndex:0];
                             if([animationQueue count]>0) {
                                 void (^nextAction)() = [animationQueue objectAtIndex:0];
                                 nextAction();
                             }
                         }];
    };

    [animationQueue addObject:showMessageBlock];
    if([animationQueue count]==1) {
        showMessageBlock();
    }
}