用自定义对象sortingNSArray

在我的Xcode项目中，我有以下类：

地址

@interface LDAddress : NSObject{ NSString *street; NSString *zip; NSString *city; float latitude; float longitude; } @property (nonatomic, retain) NSString *street; @property (nonatomic, retain) NSString *zip; @property (nonatomic, retain) NSString *city; @property (readwrite, assign, nonatomic) float latitude; @property (readwrite, assign, nonatomic) float longitude; @end 

位置

 @interface LDLocation : NSObject{ int locationId; NSString *name; LDAddress *address; } @property (readwrite, assign, nonatomic) int locationId; @property (nonatomic, retain) LDAddress *address; @property (nonatomic, retain) NSString *name; @end 

在UITableViewController的子类中，有一个NSArray包含许多LDLocations未sorting的对象。 现在，我想根据LDAddress属性城市对NSArray的对象进行升序sorting。

我怎样才能使用NSSortDescriptorsorting数组？ 我尝试了以下，但sorting数组时，应用程序转储。

 NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Address.city" ascending:YES]; [_locations sortedArrayUsingDescriptors:@[sortDescriptor]]; 

Answer 1

尝试使第一个关键小写。

 NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"address.city" ascending:YES]; 

Answer 2

您也可以用块对数组sorting：

  NSArray *sortedLocations = [_locations sortedArrayUsingComparator: ^(LDAddress *a1, LDAddress *a2) { return [a1.city compare:a2.city]; }]; 

Answer 3

这将允许sorting多种types。 就像我们需要根据时间对电影进行sorting，如果时间相等，则需要按名称sorting。

 NSArray *sortedArray = [childrenArray sortedArrayUsingComparator:^NSComparisonResult(id a, id b) { NSNumber *first = [NSNumber numberWithLong:[(Movie*)a timeInMillis]]; NSNumber *second = [NSNumber numberWithLong:[(Movie*)b timeInMillis]]; NSComparisonResult result = [first compare:second]; if(result == NSOrderedSame){ result = [((NSString*)[(Movie*)a name] ) compare:((NSString*)[(Movie*)b name])]; } return result; }]; 

Answer 4

 -(NSArray*)sortedWidgetList:(NSArray*)widgetList { NSSortDescriptor *firstDescriptor = [[NSSortDescriptor alloc] initWithKey:@"itemNum" ascending:YES]; NSArray *sortDescriptors = [NSArray arrayWithObjects:firstDescriptor, nil]; NSArray *sortedArray = [widgetList sortedArrayUsingDescriptors:sortDescriptors]; return sortedArray; }