如何在设备旋转后以编程方式创建的 UIButtons 保持在屏幕底部？

Question

出于某种原因，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。我发现如果我想让按钮处于完全相同的位置，如果它们是在 Interface Builder 中创建的，我必须像这样定义它们的框架：

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，我基本上是取整个屏幕的高度，减去状态和导航栏的高度，然后这些按钮的高度和屏幕底端的空间来设置Y坐标两个按钮。我正在使用类似的技术来确定右侧按钮的X 坐标。三个宏定义如下：

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

最后，我有方法(void)didRotate:(NSNotification *)notification，每当用户旋转设备时都会调用该方法，并且我知道我需要为按钮设置新框架以供他们重绘（或者我可以吗？也许它是通过一些转换来完成的？ ) 但无论我尝试将新框架分配给什么值，我都无法正确处理。我最近的尝试是这样的（缩短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];

}

但无论我尝试为origin.x 和origin.y 分配什么值，按钮总是出现在屏幕外或完全奇怪的位置。奇怪的是，如果我为这两个属性都设置了100 的值，则按钮不会出现在距屏幕左上角大约 100 点的位置，而是在我看来完全随机的地方。似乎我不知道当设备旋转时坐标系会发生什么……嗯……这就是我想请你介入并保存我的应用程序的地方！ :-)

PS：状态和导航栏从纵向（客户需求，客户获得）保持在其位置，这就是为什么它们不包括在新的原点计算中。

Answer 1

您需要为您的按钮设置适当的 UIViewAutoresizingMask 看到这个answer