iPod: NS_NONATOMIC_IPHONEONLY是什么意思？在iPod Touch上使用这样的属性安全吗？

Question

在属性部分下的CLLocation Class Reference中，它为coordinate提供了以下内容：

coordinate
The geographical coordinate information. (read-only)

@property(readonly, NS_NONATOMIC_IPHONEONLY) CLLocationCoordinate2D coordinate
Discussion
When running in the simulator, Core Location assigns a fixed set of coordinate values to this property. You must run your application on an iOS-based device to get real location values.

Special Considerations
In iOS, this property is declared as nonatomic. In Mac OS X, it is declared as atomic.

我只是好奇这是什么意思：@property(readonly, NS_NONATOMIC_IPHONEONLY)。具体地说就是NS_NONATOMIC_IPHONEONLY部分。在我看来，我可以通过iPod触摸屏访问它。

我是不是遗漏了什么？在iPod触摸屏上使用它安全吗？

Answer 1

在across和iOS (née iPhone OS)之间共享CoreLocation。

这里，NS_NONATOMIC_IPHONEONLY只是指在iOS上是非原子的，在Mac上是原子的。这里的iPhone只指iOS，而不是iPhone和iPod touch。

它在TargetConditionals.h中定义如下。

// Marks APIs whose iPhone versions are nonatomic, that is cannot be set/get from multiple threads safely without additional synchronization
#if !defined(NS_NONATOMIC_IPHONEONLY)
    #if TARGET_OS_IPHONE
    #define NS_NONATOMIC_IPHONEONLY nonatomic
    #else
    #define NS_NONATOMIC_IPHONEONLY
    #endif
#endif