如何从Objective-C的“（void）”方法中将NSString值转换为“（BOOL）”方法？

Question

我想将“城市”的价值变成“当前位置”。

- (void)reverseGeocoder:(MKPlacemark *)placemark { 
    NSString *city = [myPlacemark.addressDictionary objectForKey:(NSString*) kABPersonAddressCityKey]; 
} 

- (BOOL)fetchAndParseRSS {   
    NSString *currentLocation; // I want 'city' here. 
    return YES; 
} 

Answer 1

你为什么从你的reverseGeocoder消息返回void？我会写这样的：

- (NSString*)reverseGeocoder:(Placemark*)myPlacemark 
{ 
    // assuming myPlacemark is holding a reference to the dictionary (so no need to retain) 
    NSString *city = [myPlacemark.addressDictionary objectForKey:kABPersonAddressCityKey]; 
    return city; 
} 

-(BOOL)fetchAndParseRss 
{ 
    // you need to get myPlacemark from somewhere, presumably from the geocode request? 
    Placemark * myPlacemark = [self getPlacemark]; 

    NSString * CurrentLocation = [self reverseGeocoder:myPlacemark]; 
} 

在这段代码中，我假设Placemark是一个类，它有一个addressDictionary NSDictionary定义为一个属性。

如果你真的需要这个消息来返回一个void *，那么你将从NSString *转换为void *然后再返回。

- (void*)reverseGeocoder:(Placemark*)myPlacemark 
{ 
    // assuming myPlacemark is holding a reference to the dictionary (so no need to retain) 
    NSString *city = [myPlacemark.addressDictionary objectForKey:kABPersonAddressCityKey]; 
    return (void*)city; 
} 

然后将它转换回一个NSString当你将它（不知道你为什么会这么做）：

-(BOOL)fetchAndParseRss 
{ 
    // you need to get myPlacemark from somewhere, presumably from the geocode request? 
    Placemark * myPlacemark = [self getPlacemark]; 

    NSString * CurrentLocation = (NSString*)[self reverseGeocoder:myPlacemark]; 
}