iPhone 3.0指南针：如何获得标题？ [英] iPhone 3.0 Compass: how to get a heading?

问题描述

我对Objective-C比较陌生，对它真的不太了解，所以我为这可能是一个非常业余的问题道歉。

I'm relatively new to Objective-C and really don't know much about it yet, so I apologise for what is probably a really amateurish question.

我正在尝试从CLHeading和CLLocationDirection获取磁路。但是我得到这行代码的编译错误：

I'm trying to get the magnetic heading from CLHeading and CLLocationDirection. However I'm getting compile errors for this line of code:

locationLabel.text = [[[location course] magneticHeading] stringValue];

错误包括：

warning: invalid receiver type 'CLLocationDirection'  
error: cannot convert to a pointer type

我真的不明白我在这里做错了什么。请帮助！

I don't really understand what I'm doing wrong here. Please help!

推荐答案

以下是使用指南针所需的步骤。

Here are the steps needed to use the compass.

1）检查可用性：如果位置管理器的 headingAvailable 属性为YES，则可以使用指南针。

1) check the availability: if the headingAvailable property of the location manager is YES, then you can use the compass.

2）使用位置管理器方法 - （void）startUpdatingHeading 开始接收您要搜索的信息

2) use the location manager method -(void) startUpdatingHeading to begin receiving the information you are searching for

3）实际使用委托方法检索此信息（不要忘记将自己设置为委托）

3) actually retrieve this information using the delegate method (do not forget to set yourself as the delegate)

 - (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading

希望这会有所帮助。

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