gistfile1.m

//
//  TMSerialAnimationQueue.h
//  Orangina
//
//  Created by Bryan Irace on 10/9/13.
//  Copyright (c) 2013 Tumblr. All rights reserved.
//

/**
 Contains boilerplate for performing animations serially, without blocking the main thread.
 */
@interface TMSerialAnimationQueue : NSObject

- (void)addAnimationBlock:(void (^)(void))animation;

@end

gistfile2.m

//
//  TMSerialAnimationQueue.m
//  Orangina
//
//  Created by Bryan Irace on 10/9/13.
//  Copyright (c) 2013 Tumblr. All rights reserved.
//

#import "TMSerialAnimationQueue.h"

@interface TMSerialAnimationQueue()

@property (nonatomic) dispatch_queue_t queue;
@property (nonatomic) dispatch_semaphore_t semaphore;

@end

@implementation TMSerialAnimationQueue

#pragma mark - NSObject

- (id)init {
    if (self = [super init]) {
        self.queue = dispatch_queue_create(NULL, DISPATCH_QUEUE_SERIAL);
    }
    
    return self;
}

#pragma mark - TMSerialAnimationQueue

- (void)addAnimationBlock:(void (^)(void))animation {
    if (!animation) {
        return;
    }
    
    dispatch_async(self.queue, ^{
        self.semaphore = dispatch_semaphore_create(0);
        
        dispatch_async(dispatch_get_main_queue(), ^{
            animation();
            dispatch_semaphore_signal(self.semaphore);
        });
        
        dispatch_semaphore_wait(self.semaphore, DISPATCH_TIME_FOREVER);
        self.semaphore = nil;
    });
}

@end

This doesn't let you do the following:

[animationQueue addAnimationBlock:^{
    [UIView animateWithDuration:TMAnimationDuration
                          delay:0
                        options:UIViewAnimationOptionCurveEaseInOut
                     animations:^{
                         label.alpha = 1;
                         label.frameY -= animationDistance;

                     } completion:^(BOOL finished) {
                         [UIView animateWithDuration:TMAnimationDuration
                                               delay:TMAnimationDelay
                                             options:UIViewAnimationOptionCurveEaseInOut animations:^{
                                                 label.alpha = 0;
                                                 label.frameY += animationDistance;

                                             } completion:^(BOOL finished2) {
                                                 [label removeFromSuperview];

                                                 [weakSelf.animationQueue finish];
                                             }];
                     }];
}];