我如何在ios4中绘制像iphone 3gs这样的指南针？

Question

我正试图在iphone 3gs或iphone4中制作像罗盘一样的视图。你知道有人怎么开始吗？我找不到太多关于这个问题的信息...我只想画一个跟随北方的箭头。 我正在使用ios 4.0

提前致谢

Answer 1

使用以下命令开始标题更新：

if([CLLocationManager headingAvailable]) {
    CLLocationManager *locationManager = [[CLLocationManager alloc] init];

    // myDelegateObject is an instance of a class implementing the CLLocationManagerDelegate protocol
    locationManger.delegate = myDelegateObject;
    [locationManager startUpdatingHeading];
}

在您的某个类上实现CLLocationManagerDelegate协议 - 特别是：

-(void)locationManager:(CLLocationManager*)manager didUpdateHeading:(CLHeading*)heading {
    // CLLocationDirection is a double typedef
    CLLocationDirection headingInDegrees = heading.magneticHeading;

    // you'll have to implement this in some fashion...
    [myCompassViewController rotateCompassImageToHeading:headingInDegrees];
}