拿到当前正在显示的控制器，不管是push进去的，还是present进去的都能拿到
- (UIViewController*)getVisibleViewControllerFrom:(UIViewController*)vc {
if ([vc isKindOfClass:[UINavigationController class]]) {
return [self getVisibleViewControllerFrom:[((UINavigationController*) vc) visibleViewController]];
}elseif([vcisKindOfClass:[UITabBarControllerclass]]){
return [self getVisibleViewControllerFrom:[((UITabBarController*) vc) selectedViewController]];
}else{
if (vc.presentedViewController) {
return [self getVisibleViewControllerFrom:vc.presentedViewController];
}else{
returnvc;
}
}
}
