使用自定义对象对NSArray进行排序

问题描述

在我的Xcode项目中，我有以下课程：

In my Xcode project I have the following classes:

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包含很多未分类的LDLocations对象。现在，我想根据LDAddress的属性 city 对NSArray的对象进行升序排序。

In an subclass of UITableViewController, there is a NSArray containing a lot of unsorted objects of LDLocations. Now, I want to sort the NSArray's objects ascending based on the property city of a LDAddress.

如何使用NSSortDescriptor对数组进行排序？
我尝试了以下方法，但是在排序数组时应用程序转储。

How can I sort the array using NSSortDescriptor?I tried the following, but the app dumps when sorting the array.

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

推荐答案

尝试将第一个键设为小写。

Try making the first key lowercase.

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

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