Blocksの遅延実行 - performBlock: afterDelay:

NSObject のカテゴリあたりに。

/*!
 * @method performBlock:afterDelay:
 */
- (void)performBlock:(void (^)(void))block afterDelay:(NSTimeInterval)delay {
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, delay * NSEC_PER_SEC), dispatch_get_current_queue(), block);
}

/*!
 * @method performBlock:withObject:afterDelay:
 */
- (void)performBlock:(void (^)(id obj))block withObject:(id)object afterDelay:(NSTimeInterval)delay {
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, delay * NSEC_PER_SEC), dispatch_get_current_queue(), ^{block(object);});
}

参考

• http://cocoadays.blogspot.jp/2010/08/blocks.html
• http://stackoverflow.com/questions/4139219/how-do-you-trigger-a-block-after-a-delay-like-performselectorwithobjectafter