resolve loop references in NSTimer

NSTimer+ZDUtility

@interface NSTimer (ZDUtility)

+ (NSTimer *)zd_scheduledTimerWithTimeInterval:(NSTimeInterval)seconds
                                         block:(void (^)(NSTimer *timer))block
                                       repeats:(BOOL)repeats;

+ (NSTimer *)zd_timerWithTimeInterval:(NSTimeInterval)seconds
                                block:(void (^)(NSTimer *timer))block
                              repeats:(BOOL)repeats;

@end

@implementation NSTimer (ZDUtility)

#pragma mark - Public Method

+ (NSTimer *)zd_scheduledTimerWithTimeInterval:(NSTimeInterval)seconds block:(void (^)(NSTimer *timer))block repeats:(BOOL)repeats {
    return [NSTimer scheduledTimerWithTimeInterval:seconds target:self selector:@selector(executeTimerBlock:) userInfo:[block copy] repeats:repeats];
}

+ (NSTimer *)zd_timerWithTimeInterval:(NSTimeInterval)seconds block:(void (^)(NSTimer *timer))block repeats:(BOOL)repeats {
    return [NSTimer timerWithTimeInterval:seconds target:self selector:@selector(executeTimerBlock:) userInfo:[block copy] repeats:repeats];
}

#pragma mark - Private Method

+ (void)executeTimerBlock:(NSTimer *)timer {
    if ([timer userInfo]) {
        void(^timerBlock)(NSTimer *) = (void(^)(NSTimer *))[timer userInfo];
        timerBlock(timer);
    }
}