iOS开发：CoreMotion与MapKit框架实战

### iOS开发：Core Motion与Map Kit框架实战 #### 1. Core Motion框架应用 Core Motion框架能让开发者获取设备的多种运动数据，如姿态、旋转速率、加速度和磁场等。下面将介绍如何使用该框架获取设备运动数据、设置参考帧，以及实现一个利用重力移动标签的应用。 ##### 1.1 访问设备运动数据 要访问设备运动数据，需进行以下操作： 1. **初始化运动管理器**：使用`CMMotionManager`类来管理设备运动数据的更新。 2. **启动和停止更新**：通过`startDeviceMotionUpdatesToQueue:withHandler:`方法启动更新，并通过`stopDeviceMotionUpdates`方法停止更新。 3. **获取数据**：在更新处理程序中，可获取设备的姿态、旋转速率、加速度和磁场等数据。 以下是示例代码： ```objc - (void)startUpdates { // Start device motion updates if ([self.motionManager isDeviceMotionAvailable]) { // Update twice per second [self.motionManager setDeviceMotionUpdateInterval:1.0/2.0]; [self.motionManager startDeviceMotionUpdatesToQueue:[NSOperationQueue mainQueue] withHandler: ^(CMDeviceMotion *deviceMotion, NSError *error) { // Update attitude labels self.rollLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.attitude.roll]; self.pitchLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.attitude.pitch]; self.yawLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.attitude.yaw]; // Update rotation rate labels self.xRotLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.rotationRate.x]; self.yRotLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.rotationRate.y]; self.zRotLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.rotationRate.z]; // Update user acceleration labels self.xGravLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.gravity.x]; self.yGravLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.gravity.y]; self.zGravLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.gravity.z]; // Update user acceleration labels self.xAccLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.userAcceleration.x]; self.yAccLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.userAcceleration.y]; self.zAccLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.userAcceleration.z]; // Update magnetic field labels self.xMagLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.magneticField.field.x]; self.yMagLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.magneticField.field.y]; self.zMagLabel.text = [NSString stringWithFormat:@"%f", deviceMotion.magneticField.field.z]; }]; } } -(void)stopUpdates { if ([self.motionManager isDeviceMotionAvailable] && [self.motionManager isDeviceMotionActive]) { [self.motionManager stopDeviceMotionUpdates]; } } ``` 在应用委托的`applicationWillResignActive:`和`applicationDidBecomeActive:`方法中分别调用`stopUpdates`和`startUpdates`方法，以确保在应用进入后台和前台时正确处理更新。 ```objc - (void)applicationWillResignActive:(UIApplication *)application { [self.viewController stopUpdates]; } - (void)applicationDidBecomeActive:(UIApplication *)application { [self.viewController startUpdates]; } ``` ##### 1.2 设置参考帧 虽然不是必需的，但可以为姿态数据指定参考帧。通过`startDeviceMotionUpdatesUsingReferenceFrame:toQueue:withHandler:`方法来设置参考帧。参考帧参数有以下几种可能的值： | 参考帧 | 描述 | | ---- | ---- | | CMAttitudeReferenceFrameXArbitraryZVertical | z轴垂直，x轴任意方向，设备平放且正面朝上 | | CMAttitudeReferenceFrameXArbitraryCorrectedZVertical | 与上一个值相同，但使用磁力计提供更高的精度，增加CPU使用率，需要磁力计可用并校准 | | CMAttitudeReferenceFrameXMagneticNorthZVertical | z轴垂直，x轴指向“磁北”，需要磁力计可用并校准 | | CMAttitudeReferenceFrameXTrueNorthZVertical | 与上