import

Question

我正在开发聊天类应用程序。我从服务器获取完整的消息列表并将其保存到自定义实体NSObject类的数组中。

这是我的class.h：

import

@interface ChatMessage : NSObject

@property (nonatomic, retain) NSString *msg_text;
@property (nonatomic, retain) NSDate *msg_date;
@property (nonatomic, assign) int sender_id;
@property (nonatomic, assign) int receiver_id;
@property (nonatomic, retain) NSString *msg_status;

@end

这是我的class.m：

#import "ChatMessage.h"

@implementation ChatMessage

@synthesize msg_text, msg_date, msg_status, sender_id, receiver_id;

- (id) initWithCoder: (NSCoder *)coder
{
    self = [[ChatMessage alloc] init];
    if (self != nil)
    {
        self.msg_text = [coder decodeObjectForKey:@"msg_text"];
        self.msg_date = [coder decodeObjectForKey:@"msg_date"];
        self.msg_status = [coder decodeObjectForKey:@"msg_status"];
        self.sender_id = [coder decodeIntForKey:@"sender_id"];
        self.receiver_id = [coder decodeIntForKey:@"receiver_id"];
    }
    return self;
}

- (void)encodeWithCoder: (NSCoder *)coder
{
    [coder encodeObject:msg_text forKey:@"msg_text"];
    [coder encodeObject:msg_date forKey:@"msg_date"];
    [coder encodeObject:msg_status forKey:@"msg_status"];
    [coder encodeInt:sender_id forKey:@"sender_id"];
    [coder encodeInt:receiver_id forKey:@"receiver_id"];
}

@end

我想在我的CellForRowAtIndexPath中使用“msg_date”属性对NSMutableArray的对象进行排序，然后将其显示到我的聊天列表表视图中。我将每条聊天消息的日期和时间格式设置为“2014-08-21 18:30:00”。

这是我的用于排序对象数组的代码：

NSMutableArray *unsortedArray = [[NSMutableArray alloc] init];

//sorting array with date and time
for (int i=0; i<[self.arrayChatMessages count]; i++) {

ChatMessage *chat = [[ChatMessage alloc] init];
chat = [self.arrayChatMessages objectAtIndex:i];                          

[unsortedArray addObject:chat.msg_date];
}

NSLog(@"un sorted array is = %@", unsortedArray);

NSArray *sortedArray = [unsortedArray sortedArrayUsingComparator:^(id obj1, id obj2) {
                                     return [obj2 compare:obj1];
                               }];

NSLog(@"sorted array is = %@", sortedArray);

它正在成功排序。在我的控制台中，我得到了：

un sorted array is = (
    "2014-08-21 18:28:58",
    "2014-08-21 18:27:41",
    "2014-08-21 20:10:45",
    "2014-08-21 18:30:45",
    "2014-08-29 12:27:45"
)

sorted array is = (
    "2014-08-29 12:27:45",
    "2014-08-21 20:10:45",
    "2014-08-21 18:30:45",
    "2014-08-21 18:28:58",
    "2014-08-21 18:27:41"
)

我的问题是根据这个排序的数组，我如何排序对象数组，即self.arrayChatMessages。

Answer 1

要对NSArray个自定义对象进行排序，您可以使用-sortedArrayUsingComparator:方法并依赖-compare: NSString方法的结果：

self.arrayChatMessages = [self.arrayChatMessages sortedArrayUsingComparator:^(ChatMessage *obj1, ChatMessage *obj2) {
    return [obj1.msg_date compare:obj2.msg_date];
}];

另外，我建议您使用NSString将日期属性从NSDate转换为NSDateFormatter。

错误：使用日期和时间属性对NSMutableArray的对象进行排序？

import

1 个答案: