切换横竖屏最直接的方式是调用device的setOrientation方法。但是从sdk3.0以后，这个方法转为似有API，如果要上AppStore的话，要慎用！
if ([[UIDevice currentDevice] respondsToSelector:@selector(setOrientation:)]) {
[[UIDevice currentDevice] performSelector:@selector(setOrientation:)
withObject:(id)UIInterfaceOrientationLandscapeRight];
}
第二种方式是手动的设置界面元素的旋转，包括状态栏、导航栏和视图。以下代码为从竖屏设置为横屏，坐标系是以竖屏的为基准，所以会出现负数的坐标值。
//设置状态栏旋转
[[UIApplication sharedApplication] setStatusBarOrientation:UIDeviceOrientationLandscapeRight animated:YES];
CGFloat duration = [UIApplication sharedApplication].statusBarOrientationAnimationDuration;
//设置旋转动画
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:duration];
//设置导航栏旋转
self.navigationController.navigationBar.frame = CGRectMake(-204, 224, 480, 32);
self.navigationController.navigationBar.transform = CGAffineTransformMakeRotation(M_PI*1.5);
//设置视图旋转
self.view.bounds = CGRectMake(0, -54, self.view.frame.size.width, self.view.frame.size.height);
self.view.transform = CGAffineTransformMakeRotation(M_PI*1.5);
[UIView commitAnimations];
来源： <http://blog.csdn.net/dickenslian/article/details/7407221>
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一直遇到这个问题,今天终于找到了解决方法.
在我们的项目中经常遇到横竖屏切换,而又有某个特定的界面必须是特定的显示方式(横屏或竖屏).这就需要如下的处理了.
强制转成横屏:
if ([[UIDevice currentDevice] respondsToSelector:@selector(setOrientation:)]) {
SEL selector = NSSelectorFromString(@"setOrientation:");
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[UIDevice instanceMethodSignatureForSelector:selector]];
[invocation setSelector:selector];
[invocation setTarget:[UIDevice currentDevice]];
int val = UIInterfaceOrientationLandscapeRight;
[invocation setArgument:&val atIndex:2];
[invocation invoke];
}
以上代码支持ARC哟.
方法二： 通过判断状态栏来设置视图的transform属性。
- (void)deviceOrientationDidChange: (NSNotification *)notification
{
UIInterfaceOrientation interfaceOrientation = [[UIApplication sharedApplication] statusBarOrientation];
CGFloat startRotation = [[self valueForKeyPath:@"layer.transform.rotation.z"] floatValue];
CGAffineTransform rotation;
switch (interfaceOrientation) {
case UIInterfaceOrientationLandscapeLeft:
rotation = CGAffineTransformMakeRotation(-startRotation + M_PI * 270.0 / 180.0);
break;
case UIInterfaceOrientationLandscapeRight:
rotation = CGAffineTransformMakeRotation(-startRotation + M_PI * 90.0 / 180.0);
break;
case UIInterfaceOrientationPortraitUpsideDown:
rotation = CGAffineTransformMakeRotation(-startRotation + M_PI * 180.0 / 180.0);
break;
default:
rotation = CGAffineTransformMakeRotation(-startRotation + 0.0);
break;
}
view.transform = rotation;
}
