ios开发之确定设备当前的方向

有时候我们需要判断应用程序当前的方向，可以通过获取设备当前的方向来确定，从下面的定义你可以看到UIInterfaceOrientation的定义是通过UIDeviceOrientation来完成的，有两个概念：

UIDeviceOrientation：硬件设备的方向

UIInterfaceOrientation：应用程序界面的方向

UIDeviceOrientation的定义如下：

typedef enum {    UIDeviceOrientationUnknown,    UIDeviceOrientationPortrait,            // Device oriented vertically, home button on the bottom    UIDeviceOrientationPortraitUpsideDown,  // Device oriented vertically, home button on the top    UIDeviceOrientationLandscapeLeft,       // Device oriented horizontally, home button on the right    UIDeviceOrientationLandscapeRight,      // Device oriented horizontally, home button on the left    UIDeviceOrientationFaceUp,              // Device oriented flat, face up    UIDeviceOrientationFaceDown             // Device oriented flat, face down} UIDeviceOrientation;

UIInterfaceOrientation的定义如下：

typedef enum {    UIInterfaceOrientationPortrait           = UIDeviceOrientationPortrait,    UIInterfaceOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown,    UIInterfaceOrientationLandscapeLeft      = UIDeviceOrientationLandscapeRight,    UIInterfaceOrientationLandscapeRight     = UIDeviceOrientationLandscapeLeft} UIInterfaceOrientation;

可采用下面的方式来判断当前设备的方向：

UIDevice *device = [UIDevice currentDevice];switch (device.orientation) {      case UIDeviceOrientationUnknown:          NSLog(@"Unknown");          break;            case UIDeviceOrientationFaceUp:          NSLog(@"Device oriented flat, face up");          break;              case UIDeviceOrientationFaceDown:          NSLog(@"Device oriented flat, face down");          break;               case UIDeviceOrientationLandscapeLeft:          NSLog(@"Device oriented horizontally, home button on the right");          break;              case UIDeviceOrientationLandscapeRight:          NSLog(@"Device oriented horizontally, home button on the left");          break;              case UIDeviceOrientationPortrait:          NSLog(@"Device oriented vertically, home button on the bottom");          break;              case UIDeviceOrientationPortraitUpsideDown:          NSLog(@"Device oriented vertically, home button on the top");          break;              default:          NSLog(@"cannot distinguish");          break;  } 

或者是：

UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation;  if (UIDeviceOrientationIsLandscape(deviceOrientation))     NSLog(@"The orientation is landscape");      else if(UIDeviceOrientationIsPortrait(deviceOrientation))     NSLog(@"The orientation is portrait");

UIDeviceOrientationIsLandscape的定义如下：

#define UIDeviceOrientationIsLandscape(orientation) ((orientation) == UIDeviceOrientationLandscapeLeft || (orientation) == UIDeviceOrientationLandscapeRight)

UIDeviceOrientationIsPortrait的定义如下：

#define UIDeviceOrientationIsPortrait(orientation)  ((orientation) == UIDeviceOrientationPortrait || (orientation) == UIDeviceOrientationPortraitUpsideDown)

有时候我们只需要知道当前设备是水平还是竖直放置，就可以采用第二种方法。