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这两个很常用 , 很有用 ,也比较有意思
开门见山
1.获取当前view
判断view是否在当前屏幕上显示很简单,通过window即可.
这里你可以释放一些变量或者关闭一些线程队列或者timer的释放等等.
if (!self.view.window) {
// do something
}
2.获取当前controller
当前controller
很重要,原理是通过响应者链做到的,这里不展开了.
理解概念博客里有相关文章.点击跳转
- (UIViewController *)getCurrentVC
{
UIViewController *result = nil;
UIWindow * window = [[UIApplication sharedApplication] keyWindow];
if (window.windowLevel != UIWindowLevelNormal)
{
NSArray *windows = [[UIApplication sharedApplication] windows];
for(UIWindow * tmpWin in windows)
{
if (tmpWin.windowLevel == UIWindowLevelNormal)
{
window = tmpWin;
break;
}
}
}
UIView *frontView = [[window subviews] objectAtIndex:0];
id nextResponder = [frontView nextResponder];
if ([nextResponder isKindOfClass:[UIViewController class]])
result = nextResponder;
else
result = window.rootViewController;
return result;
}
