CAAnimationのカテゴリとしてblocks定義。
delegate処理する為にSingleton Class (ここではEEAnimationHandler)を作る。
implement側のdelegate呼ばれるタイミングでblocks呼んであげる。

EEAnimationHandler.h

typedef void (^EEAnimationDidStopHandlerBlock)(CAAnimation *anim, BOOL finished);
typedef void (^EEAnimationDidStartHandlerBlock)(CAAnimation *anim);

@interface CAAnimation (handle)

@property (nonatomic, strong) EEAnimationDidStartHandlerBlock startHandlerBlock;
@property (nonatomic, strong) EEAnimationDidStopHandlerBlock stopHandlerBlock;
@property (nonatomic, strong) NSString *animationKey;
@property (nonatomic, weak) CALayer *addedLayer;

@end

@interface EEAnimationHandler : NSObject

+ (EEAnimationHandler *)sharedHandler;
- (void)registerAnimation:(CAAnimation *)animation toLayer:(CALayer *)layer forKey:(NSString *)key;

@end

EEAnimationHandler.m

@implementation EEAnimationHandler

- (void)registerAnimation:(CAAnimation *)animation toLayer:(CALayer *)layer forKey:(NSString *)aKey
{
    animation.animationKey = key;
    animation.addedLayer = layer;
    animation.delegate = self;
    [layer addAnimation:animation forKey:aKey];
}

#pragma mark - Animation Delegate
- (void)animationDidStart:(CAAnimation *)anim
{
    if (anim.startHandlerBlock) anim.startHandlerBlock(anim);
}

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
    if (anim.stopHandlerBlock) anim.stopHandlerBlock(anim, flag);
}

ざっくりはこんな感じ。
githubにアップしてますのでぜひ。