Question

使用Xcode 4.2.1 iPad iOS 5.0.1，创建一个新的“单一视图”iPad项目。在控制器中，添加：

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return YES;
}

- (void) dumpView: (UIView *) view {
    CGRect frame = view.frame ;
    CGRect bounds = view.bounds ;
    CGPoint center = view.center ;

    NSLog(@"view [%@]:%d frame=%@ bounds=%@ center=%@"
          ,   NSStringFromClass(view.class)
          ,   [view hash]
          ,   NSStringFromCGRect(frame)
          ,   NSStringFromCGRect(bounds)
          ,   NSStringFromCGPoint(center)) ;
}

- (void) didRotateFromInterfaceOrientation:(UIInterfaceOrientation) fromInterfaceOrientation {

    NSLog(@"INViewController.didRotateFromInterfaceOrientation: %d to %d", fromInterfaceOrientation, self.interfaceOrientation) ;
    [self dumpView: self.view] ;
    [self dumpView: self.view.superview] ;
}

运行它，旋转设备，您将获得：

INViewController.didRotateFromInterfaceOrientation: 2 to 4
view [UIView]   bounds={{0, 0}, {1024, 748}} center={394, 512}
view [UIWindow] bounds={{0, 0}, {768, 1024}} center={384, 512}

换句话说，UIView的坐标“按预期交换到横向”，但其父UIWindow仍声称处于纵向模式......

此外，UIView大小似乎有点错误：应该在20的y坐标是0 ...

任何人都知道这意味着什么？

Answer 1

UIWindow的坐标系始终处于纵向。它通过设置rootViewController的视图变换来应用旋转。例如，我使用单视图模板创建了一个测试应用程序并运行它。纵向：

(gdb) po [[(id)UIApp keyWindow] recursiveDescription]
<UIWindow: 0x9626a90; frame = (0 0; 768 1024); layer = <UIWindowLayer: 0x9626b80>>
   | <UIView: 0x96290e0; frame = (0 20; 768 1004); autoresize = W+H; layer = <CALayer: 0x96286a0>>

左转后：

(gdb) po [[(id)UIApp keyWindow] recursiveDescription]
<UIWindow: 0x9626a90; frame = (0 0; 768 1024); layer = <UIWindowLayer: 0x9626b80>>
   | <UIView: 0x96290e0; frame = (0 0; 748 1024); transform = [0, 1, -1, 0, 0, 0]; autoresize = W+H; layer = <CALayer: 0x96286a0>>

右转后：

(gdb) po [[(id)UIApp keyWindow] recursiveDescription]
<UIWindow: 0x9626a90; frame = (0 0; 768 1024); layer = <UIWindowLayer: 0x9626b80>>
   | <UIView: 0x96290e0; frame = (20 0; 748 1024); transform = [0, -1, 1, 0, 0, 0]; autoresize = W+H; layer = <CALayer: 0x96286a0>>

注意旋转设备时如何设置变换（到90度旋转矩阵）。

关于UIView大小的问题：视图的边界位于其自己的坐标空间中，默认情况下，视图的边界'原点位于其坐标空间的原点（0,0）。视图的框架位于其父级的坐标空间中。您可以在上面的递归描述中看到您期望的20，或直接打印框架：

(gdb) p (CGRect)[[[[(id)UIApp keyWindow] subviews] lastObject] frame]
$2 = {
  origin = {
    x = 0, 
    y = 20
  }, 
  size = {
    width = 768, 
    height = 1004
  }
}

旋转UIView坐标后，但UIWindow不是？

1 个答案: