iOS 获取屏幕的朝向

      //检测屏幕朝向变化
      -(void)startDeviceOrientationChangeListener {
          [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
          [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceOrientationDidChange) name:UIDeviceOrientationDidChangeNotification object:nil];
      }
      -(void)deviceOrientationDidChange {
         /*
       typedef NS_ENUM(NSInteger, UIDeviceOrientation) {
       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 orientation = [UIDevice currentDevice].orientation;
         NSMutableString *orientationDescription = [[NSMutableString alloc] initWithFormat:@"%ld ", orientation];
         switch (orientation) {
             case UIDeviceOrientationUnknown:
                  [orientationDescription appendFormat:@"%@", @"UIDeviceOrientationUnknown"];
                 break;
             case UIDeviceOrientationPortrait:
                  [orientationDescription appendFormat:@"%@", @"UIDeviceOrientationPortrait"];
                 break;
             case UIDeviceOrientationPortraitUpsideDown:
                  [orientationDescription appendFormat:@"%@", @"UIDeviceOrientationPortraitUpsideDown"];
                 break;
             case UIDeviceOrientationLandscapeLeft:
                  [orientationDescription appendFormat:@"%@", @"UIDeviceOrientationLandscapeLeft"];
                 break;
             case UIDeviceOrientationLandscapeRight:
                  [orientationDescription appendFormat:@"%@", @"UIDeviceOrientationLandscapeRight"];
                 break;
             case UIDeviceOrientationFaceUp:
                  [orientationDescription appendFormat:@"%@", @"UIDeviceOrientationFaceUp"];
                 break;
             case UIDeviceOrientationFaceDown:
                  [orientationDescription appendFormat:@"%@", @"UIDeviceOrientationFaceDown"];
                 break;
          }
         NSLog(@"%@", orientationDescription);
      }
  
 

我在模拟器上进行测试时发现：第一次会先打印“UIDeviceOrientationUnknown”，接着立马打印“UIDeviceOrientationPortrait”，间隔只有3毫秒左右（当时并没有改变设备方向）

2016-06-21 00:34:31.782 SensorDemo[599:15448] 0 UIDeviceOrientationUnknown
2016-06-21 00:34:31.785 SensorDemo[599:15448] 1 UIDeviceOrientationPortrait

文章来源: blog.csdn.net，作者：福州-司马懿，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/chy555chy/article/details/51724284