如何在運行時從超級視圖中刪除視圖？

Question

基於互聯網連接，我必須刪除或添加子視圖到超級視圖。

我可以在運行時添加子視圖。 但不能從子視圖中刪除。

我試過這樣

if ([statusString isEqualToString:@"Access Not Available"]){
   view = [[UIView alloc]initWithFrame:CGRectMake(0, navigationView.frame.size.height, self.view.frame.size.width, 50)];
    [self.view addSubview:view];
    view.backgroundColor = [UIColor lightGrayColor];
}else{
    [[NSOperationQueue mainQueue] addOperationWithBlock:^ {

        [view removeFromSuperview];
    }];
}

但它並沒有從超級視圖中刪除。

我怎樣才能做到這一點？

Answer 1

///in view did load
view_NoConnectn = [[UIView alloc]init];
[view_NoConnectn setBackgroundColor:[UIColor whiteColor]];
[view_NoConnectn setFrame:CGRectMake(0, frameHeight, frameWidth, 35)];

UIWindow* mainWindow = [[UIApplication sharedApplication] keyWindow];
 bool isFound=false;
for(UIView *child in [mainWindow subviews])
{
    if([child tag]==007)
        isFound=true;
}
 if(!isFound)
{
    [mainWindow addSubview: btn_setting];
}

[self.navigationController.view addSubview:view_NoConnectn];



////// whereever required
   if (show){
    if (self.navigationController.view.frame.size.height == frameHeight) {
        [UIView animateWithDuration:1.0 animations:^{
            [self.navigationController.view setFrame:CGRectMake(self.navigationController.view.frame.origin.x, self.navigationController.view.frame.origin.y, self.navigationController.view.frame.size.width, frameHeight - 35)];
            [view_NoConnectn setFrame:CGRectMake(0, frameHeight-35, frameWidth, 35)];
            [self.view layoutIfNeeded];
        }];

    }

}
else
{
    if (self.navigationController.view.frame.size.height != frameHeight) {
        [UIView animateWithDuration:1.0 animations:^{
            [UIView animateWithDuration:0.8 animations:^{
                [self.navigationController.view setFrame:CGRectMake(self.navigationController.view.frame.origin.x, self.navigationController.view.frame.origin.y, self.navigationController.view.frame.size.width, frameHeight)];
                [view_NoConnectn setFrame:CGRectMake(0, frameHeight, frameWidth, 35)];
                [self.view layoutIfNeeded];
            }];
        } completion:^(BOOL finished) {
            [view_NoConnectn removeFromSuperview];
        }];
    }

}