iOS 中while 和 do while 的使用

do while 和 while 区别

do while 是首先执行一次 do 中的语句，然后再进行条件判断呢

while 是判断是否符合条件，只有符合条件才会执行语句

例子 获取当前 控制器的父控制器，获取下一个响应者，直到获取到被导航控制器管理的控制器

+ (UIViewController *)navigationContainedControllerWithController:(UIViewController *)viewcontroller
{
    UIViewController *navigationContainedVC = viewcontroller;
    NSArray *viewControlers = getCurrentNavgationCotroller().viewControllers;
    while (navigationContainedVC && [navigationContainedVC isKindOfClass:[UIViewController class]] && ![viewControlers containsObject:navigationContainedVC]) {
        navigationContainedVC = navigationContainedVC.parentViewController;
    }
    
    while (navigationContainedVC && [navigationContainedVC isKindOfClass:[UIViewController class]] && ![viewControlers containsObject:navigationContainedVC]) {
        navigationContainedVC = (UIViewController *)navigationContainedVC.nextResponder;
    }
    return navigationContainedVC;
}