iOS 指南针的制作 附带源码

#import <UIKit/UIKit.h>
#import <CoreLocation/CoreLocation.h>
@interface ViewController : UIViewController<CLLocationManagerDelegate>

@property (retain, nonatomic) UIImageView *compassImageView;
@property (retain, nonatomic) CLLocationManager *locationManager;
@end

- (void)viewDidLoad
{
[super viewDidLoad];

UIImageView* backgroundImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"BackGroundPad.png"]];
[self.view addSubview:backgroundImage];
//创建指南针图片
self.compassImageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"Compass_HD.png"]];

self.compassImageView.center = CGPointMake(370, 500);
[self.view addSubview:self.compassImageView];
//初始化locationManager并设置代理类
self.locationManager = [[CLLocationManager alloc]init];
self.locationManager.delegate = self;
if ([CLLocationManager headingAvailable]) {
//设置精度
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
//设置滤波器不工作
self.locationManager.headingFilter = kCLHeadingFilterNone;
//开始更新
[self.locationManager startUpdatingHeading];
}
else
{
UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"atention" message:@"compass not Available" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles: nil];
[alert show];
}
}

//调用locationManager成员方法
- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading

{
//重置view的位置
self.compassImageView.transform = CGAffineTransformIdentity;
CGAffineTransform transform = CGAffineTransformMakeRotation(-1 * M_PI*newHeading.magneticHeading/180.0);
self.compassImageView.transform = transform;
}