调用performSelector出现PerformSelector may cause a leak because its selector is unknown

感谢http://blog.csdn.net/majiakun1/article/details/46424925的参考：

今天在调用performSelector:selector时出现了警告，看着挺不爽，于是想消除警告，在连接中看到了思路特此记录。

SEL selector = NSSelectorFromString(@"log");
    [self performSelector:selector];
警告//PerformSelector may cause a leak because its selector is   unknown
           

/* method 1 */
    SEL selector = NSSelectorFromString(@"log");
    IMP imp = [self methodForSelector:selector];
    void (*func)(id, SEL) = (void *)imp;
    func(self, selector);
           

/* method 2 */
    SEL selector = NSSelectorFromString(@"processRegion:ofView:");
    IMP imp = [_controller methodForSelector:selector];
    CGRect (*func)(id, SEL, CGRect, UIView *) = (void *)imp;
    CGRect result = func(_controller, selector, someRect, someView);
           

/* method 3 */
    #pragma clang diagnostic push
    #pragma clang diagnostic ignored "-Warc-performSelector-leaks"
    [self performSelector: NSSelectorFromString(@"log")];
    #pragma clang diagnostic pop
           

/* method 4 */
    SEL selector = NSSelectorFromString(@"log");
    SuppressPerformSelectorLeakWarning(
                                       [self performSelector:selector withObject:self]
                                       );

    //需要返回值的
    id result;
    SuppressPerformSelectorLeakWarning(
                                       [self performSelector:selector withObject:self]
                                       );
           

/* method 5 */
    [self performSelector:selector withObject:nil afterDelay:];