iOS开发 - 戏说旋屏

横竖屏切换，视图乱了怎么办？

首先，我们必须了解一下下列4种状态，它们被用来描述设备旋转方向：

对于旋屏的处理，大致分为如下几种情况和思路：

也许，你不需要旋屏支持，而希望锁定屏幕

-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation  {   return NO;  }

也许，你需要支持旋屏，或者支持部分方向的旋屏

-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {          return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);  }

也许，你的view有张背景图，旋屏时系统帮助你拉伸了图片，但是却没有管你的其它部件，比如button,你希望直接改变button的大小和位置

-(void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration  {      if (UIInterfaceOrientationIsPortrait(toInterfaceOrientation)) {          NSLog(@"现在是竖屏");          [btn setFrame:CGRectMake(213, 442, 340, 46)];      }      if (UIInterfaceOrientationIsLandscape(toInterfaceOrientation)) {          NSLog(@"现在是横屏");          [btn setFrame:CGRectMake(280, 322, 460, 35)];      }  }

也许，你并不希望用绝对坐标去约束控件，而是希望让它通过旋转自己适应屏幕的旋转

- (void)viewDidLoad  {      [super viewDidLoad];      // Do any additional setup after loading the view, typically from a nib.      UIDevice *device = [UIDevice currentDevice];       [device beginGeneratingDeviceOrientationNotifications];      //利用 NSNotificationCenter 获得旋转信号 UIDeviceOrientationDidChangeNotification      NSNotificationCenter *ncenter = [NSNotificationCenter defaultCenter];       [ncenter addObserver:self selector:@selector(orientationChanged) name:UIDeviceOrientationDidChangeNotification object:device];  }    - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation  {      return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);  }    -(void)rotation_btn:(float)n  {      UIButton *robtn = self.btn;      robtn.transform = CGAffineTransformMakeRotation(n*M_PI/180.0);  }    -(void)orientationChanged  {      UIDeviceOrientation orientaiton = [[UIDevice currentDevice] orientation];            switch (orientaiton) {          caseUIDeviceOrientationPortrait:                           [self  rotation_btn:0.0];              break;          caseUIDeviceOrientationPortraitUpsideDown:                [self  rotation_btn:90.0*2];              break;          caseUIDeviceOrientationLandscapeLeft:                   [self  rotation_btn:90.0*3];              break;          caseUIDeviceOrientationLandscapeRight:                [self  rotation_btn:90.0];              break;          default:              break;      }  }

也许，你需要autoresizesSubviews = YES

也许，你希望横竖屏有不同的布局效果，需要准备2份Subview，在不同状态去替换

当然不要忘记，需要调节设定图示中的1、2处，