如何在mainView上应用变换后得到子视图的框架？

Question

我创建了mainView objcet UIView并在其上添加了一个子视图.我在mainView上应用了变换以减小帧大小.但是mainView的子视图框架没有减少.如何减小这个子视图的大小.

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    CGFloat widthM=1200.0;
    CGFloat heightM=1800.0;
    UIView *mainView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, widthM, heightM)];
    mainView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"te.png"]];
    [self.view addSubview:mainView];
    CGFloat yourDesiredWidth = 250.0;
    CGFloat yourDesiredHeight = yourDesiredWidth *heightM/widthM;
    CGAffineTransform scalingTransform;
    scalingTransform = CGAffineTransformMakeScale(yourDesiredWidth/mainView.frame.size.width, yourDesiredHeight/mainView.frame.size.height);
     mainView.transform = scalingTransform;
    mainView.center = self.view.center;
    NSLog(@"mainView:%@",mainView);
    UIView *subMainView= [[UIView alloc] initWithFrame:CGRectMake(100, 100, 1000, 1200)];
    subMainView.backgroundColor = [UIColor redColor];
    [mainView addSubview:subMainView];
    NSLog(@"subMainView:%@",subMainView);

}

NSlog的这些观点:

mainView:<UIView: 0x8878490; frame = (35 62.5; 250 375); transform = [0.208333, 0, 0, 0.208333, 0, 0]; layer = <CALayer: 0x8879140>>
subMainView:<UIView: 0x887b8c0; frame = (100 100; 1000 1200); layer = <CALayer: 0x887c160>>

这里mainView的宽度是250,子视图的宽度是1000.但是当我在模拟器中得到输出时,子视图被正确占用,但它没有穿过mainView.怎么可能？如何在转换后获得关于mainView框架的子视图框架？

Answer 1

您所看到的是预期的行为.a的框架UIView相对于其父框架,因此在将转换应用于其superview时它不会更改.虽然视图也会显示为"扭曲",但框架不会反映更改,因为它仍然与相对于其父级的位置完全相同.
但是,我假设你想获得相对于最顶层的视图框架UIView.在这种情况下,UIKit提供以下功能:

• – [UIView convertPoint:toView:]
• – [UIView convertPoint:fromView:]
• – [UIView convertRect:toView:]
• – [UIView convertRect:fromView:]

我将这些应用于您的示例:

CGRect frame = [[self view] convertRect:[subMainView frame] fromView:mainView];
NSLog(@"subMainView:%@", NSStringFromCGRect(frame));

这是输出:

subMainView:{{55.8333, 83.3333}, {208.333, 250}}