Question

Probably a bit of a newbie question, but .... I am writing an iPhone app which uses UITabBarController. In Interface Builder I ve setup the tab bar in MainWindow.xib. I have 4 tabs, and each one is set to load the xib for the appropriate UIViewController subclass. I have created the views in the xib files for each UIViewController subclass in Interface Builder. All is working well in that I can tap each tab and it shows the view for the correct UIViewController

But what I really want is for the view for one of the UIViewController subclasses to have a semi-transparent border of approx 30px on all 4 edges, so that it shows the edges of the view behind, kind of greyed out. IE. the first tab is the main application, and that takes up the whole screen (minus the status and tab bar areas).Tab 2 is to save, and I want it to look like a small modal window over the top of the main app. (If I were doing this as a html web app, the terminology and technology I d be using would be a jQuery overlay)

这是否有意义?

我用目前的ModalViewController玩.,但情况更糟,因为它接受包括地位和禁区在内的整个屏幕。

Any help or pointers very much appreciated Cheers

Nathan

Answer 1

Your UIViewController cannot be transparent to the view below it because the iphone may unload the view below it that is not currently being shown (to save memory).

我所采用的最佳解决办法是,在你推动你的新的观点控制者之前,了解当前的看法,然后将这种看法作为背景形象(激发透明度)。这里我是如何落实的:

NewViewController *newView = [[NewViewController alloc] init];
shareVC.imageBackground = [Utilities getScreenshot:self.view];
[self presentModalViewController:newView animated:YES];
[newView release];

接着, 主计长这样做(关于DidLoad、WillAppear等人的看法):

[imageView setImage:imageBackground];

页: 1

+(UIImage *)getScreenshot:(UIView *)_view {
    //take a screenshow of the parent view so we can add it as a background to the modal view
    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
        UIGraphicsBeginImageContextWithOptions(_view.window.bounds.size, NO, [UIScreen mainScreen].scale);
    else
        UIGraphicsBeginImageContext(_view.window.bounds.size);
    [_view.window.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

You then need to setup your new view with a UIImageView as the background and pick the right Alpha value for that imageView to make it appear like it s transparent.

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