iPod:NS_NONATOMIC_IPHONEONLY是什么意思？在iPod Touch上使用这样的属性是否安全？

Question

在CLLocation Class Reference属性部分下面,它的内容是coordinate:

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.

我只是好奇这意味着什么:@property(readonly, NS_NONATOMIC_IPHONEONLY).特别是NS_NONATOMIC_IPHONEONLY部分.在我看来,我可以从iPod touch访问它.

我错过了什么吗？从iPod touch使用它是否安全？

Answer 1

CoreLocation在Mac OS X和iOS(néeiPhoneOS)上共享.

在这里,NS_NONATOMIC_IPHONEONLY只表示iOS和非Mac OS X上的原子是非原子的.这里的iPhone仅指iOS,而不是iPhone和iPod touch.

它在TargetConditionals.h中定义为此.

// 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