ios - 设备旋转后，如何将以编程方式创建的UIButton保留在屏幕底部？

Question

由于某种原因，我必须以编程方式而不是在.xib / .storyboard文件中创建两个UIButton，并且我希望它们始终位于屏幕底部。我发现，如果要将按钮放置在与在Interface Builder中创建的按钮完全相同的位置，则必须定义它们的框架，如下所示:

CGRect captureCodeFrame = [[self captureCodeButton] frame];
CGRect captureReceiptFrame = [[self captureReceiptButton] frame];

captureCodeFrame.origin.x = MARGIN;
captureCodeFrame.origin.y = [[UIScreen mainScreen] bounds].size.height - [[UIApplication sharedApplication] statusBarFrame].size.height - [[[self navigationController] navigationBar] frame].size.height - BUTTON_HEIGHT - MARGIN;
captureReceiptFrame.origin.x = [[UIScreen mainScreen] bounds].size.width - BUTTON_WIDTH - MARGIN;
captureReceiptFrame.origin.y = [[UIScreen mainScreen] bounds].size.height - [[UIApplication sharedApplication] statusBarFrame].size.height - [[[self navigationController] navigationBar] frame].size.height - BUTTON_HEIGHT - MARGIN;

[[self captureCodeButton] setFrame:captureCodeFrame];
[[self captureReceiptButton] setFrame:captureReceiptFrame];

换句话说，我基本上是考虑整个屏幕的高度，减去状态和导航栏的高度，然后减去这些按钮的高度以及屏幕底端的空间，以设置两个按钮的 Y坐标。我正在使用类似的技术来确定右键的 X坐标。这三个宏的定义如下:

#define MARGIN 20
#define BUTTON_HEIGHT 30
#define BUTTON_WIDTH 136

最后，我有一个 (void)didRotate:(NSNotification *)notification方法，每当用户旋转设备时都会调用该方法，并且我了解我需要为按钮设置新框架以使其重绘(或者我？也许是通过某种转换完成的？)，但是无论如何我尝试将新框架分配给它们的值，但我做对了。我最近的尝试是这样的(简称为仅包括左横向模式):

- (void)didRotate:(NSNotification *)notification
{
    UIDeviceOrientation deviceOrientation = [[UIDevice currentDevice] orientation];
    CGSize newSize = [[self view] bounds].size;
    CGRect captureCodeFrame = [[self captureCodeButton] frame];
    CGRect captureReceiptFrame = [[self captureReceiptButton] frame];

    [CATransaction begin];
    [CATransaction setAnimationDuration:0.0];
    [CATransaction setAnimationTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];

    [[self previewLayer] setPosition:CGPointMake(0.5 * newSize.width, 0.5 * newSize.height)];

    switch (deviceOrientation)
    {
        case UIDeviceOrientationPortrait:
            captureCodeFrame.origin.x = MARGIN;
            captureCodeFrame.origin.y = [[UIScreen mainScreen] bounds].size.height - [[UIApplication sharedApplication] statusBarFrame].size.height - [[[self navigationController] navigationBar] frame].size.height - BUTTON_HEIGHT - MARGIN;
            captureReceiptFrame.origin.x = [[UIScreen mainScreen] bounds].size.width - BUTTON_WIDTH - MARGIN;
            captureReceiptFrame.origin.y = [[UIScreen mainScreen] bounds].size.height - [[UIApplication sharedApplication] statusBarFrame].size.height - [[[self navigationController] navigationBar] frame].size.height - BUTTON_HEIGHT - MARGIN;

            [[self captureCodeButton] setFrame:captureCodeFrame];
            [[self captureReceiptButton] setFrame:captureReceiptFrame];
            [[self view] setTransform:CGAffineTransformMakeRotation(0)];
            [[self previewLayer] setAffineTransform:CGAffineTransformMakeRotation(0)];
            break;
        case UIDeviceOrientationLandscapeLeft:
            captureCodeFrame.origin.x = [[UIScreen mainScreen] bounds].size.width - BUTTON_WIDTH - MARGIN;
            captureCodeFrame.origin.y = MARGIN;
            // TODO: adjust captureReceiptFrame here

            [[self captureCodeButton] setFrame:captureCodeFrame];
            [[self view] setTransform:CGAffineTransformMakeRotation((CGFloat) (M_PI / 2))];
            [[self previewLayer] setAffineTransform:CGAffineTransformMakeRotation((CGFloat) (-M_PI / 2))];
            break;
        case UIDeviceOrientationLandscapeRight:
            // TODO: something should be here
            [[self view] setTransform:CGAffineTransformMakeRotation((CGFloat) (-M_PI / 2))];
            [[self previewLayer] setAffineTransform:CGAffineTransformMakeRotation((CGFloat) (M_PI / 2))];
            break;
        default:
            break;
    }

    [CATransaction commit];

}

但是，无论我尝试为 origin.x和 origin.y分配什么值，该按钮始终在屏幕外或完全怪异的位置出现。很奇怪，例如，如果我为这两个属性都输入了 100的值，则该按钮不会出现在离屏幕左上角约100个点的位置，但是在我看来这是一个完全随机的地方。似乎我不知道当设备旋转时坐标系会发生什么……好吧……这是我想请您介入并保存我的应用程序的地方! :-)

PS:状态栏和导航栏保持纵向放置(客户需求，客户满意)的位置，这就是为什么它们不包含在新起点计算中的原因。

Answer 1

您需要为按钮设置适当的UIViewAutoresizingMask
看到这个answer