iOS7,8 presentViewController 执行慢

解决办法:

1, 使用GCD用主线程跳转

dispatch_async(dispatch_get_main_queue(), ^{
     //跳转代码
     ...
});

2, 召唤主线程, 使用performSelector在主线程随便执行一个方法

[self performSelector:@selector(anyMethod) onThread:[NSThread mainThread] withObject:nil waitUntilDone:NO];