iOS开发中对NSArray或者NSMutableArray中的内容排序

原文引用至               http://blog.unieagle.net/2012/05/10/ios开发中对nsarray或者nsmutablearray中的内容排序/

NSMutableArray *feedsBuffer;
//初始化buffer以及填充数据
//.......
//排序只需要两句话:已针对数组内对象的publishTime属性(NSDate)排序为例：
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"publishTime" ascending:NO];
[feedsBuffer sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];

//假如feedsBuffer是NSArray，那么有一个方法是

NSArray *sortedArray = [feedsBuffer sortedArrayUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];

//如果排序的依据比较复杂，那么可以使用Block进行大小判断自定义：

[feedsBuffer sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
//返回三者其一:NSOrderedAscending, NSOrderedSame, NSOrderedDescending
return NSOrderedSame;
}];

我的项目是要对未读消息进行靠前排序

- (void)reloadNuReadMsgCount
{
    NSMutableDictionary *sessionDic = [[IMMsgDBAccess sharedInstance] loadAllSessions];
    NSArray *allSession = [sessionDic allValues];
    for (NSMutableDictionary *dic in _dataArray) {
        for ( ECSession* session in allSession) {
            NSString *sessionId = session.sessionId;
             NSString *ronggroupid = [dic objectForKey:@"ronggroupid"];
            if ([sessionId isEqualToString:ronggroupid]) {
                [dic setValue:[NSString stringWithFormat:@"%ld", (long)session.unreadCount] forKey:MsgUnReadCount];
            }
        }
    }
    // 根据字典里的  MsgUnReadCount  属性来排序未读消息
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"MsgUnReadCount" ascending:NO];
    [_dataArray sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
    
    NSLog(@"%@",_dataArray);
    
    [_contentTableView reloadData];
}