如何從Objective-C的「（void）」方法中將NSString值轉換爲「（BOOL）」方法？

Question

我想將「城市」的價值變成「當前位置」。

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

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

Answer 1

你爲什麼從你的reverseGeocoder消息返回void？我會寫這樣的：

- (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]; 
} 

在這段代碼中，我假設Placemark是一個類，它有一個addressDictionary NSDictionary定義爲一個屬性。

如果你真的需要這個消息來返回一個void *，那麼你將從NSString *轉換爲void *然後再返回。

- (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; 
} 

然後將它轉換回一個NSString當你將它（不知道你爲什麼會這麼做）：

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

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