Blocks category for NSObject

NSObject+Blocks.h

// credits to Matthias Plappert

#import <Foundation/Foundation.h>

@interface NSObject (PWBlocks)

- (void)performBlock:(void (^)(void))block afterDelay:(NSTimeInterval)delay;

@end

NSObject+Blocks.m

#import "NSObject+Blocks.h"

@implementation NSObject (PWBlocks)

- (void)performBlock:(void (^)(void))block afterDelay:(NSTimeInterval)delay
{
    int64_t delta = (int64_t)(NSEC_PER_SEC * delay);
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, delta), dispatch_get_main_queue(), block);
}

@end