如何删除 NSMutableArray 中具有相同属性值但只有一个的所有对象

我有一个带有 url 字符串属性和标题的历史对象。我想搜索 URL 包含搜索字符串的对象的所有历史记录，然后删除所有重复项。

例子： 我有一系列历史对象，其中 20 个都是“https://www.google.com https://www.google.com” 和 4 是 “https://www.google.com/#q=search https://www.google.com/#q=search"，我想返回一个数组，其中只有一个 url 值为 " 的对象https://www.google.com https://www.google.com" 和一个 url 值 "https://www.google.com/#q=search https://www.google.com/#q=search"

这是我当前的代码，用于搜索历史记录并返回与字符串匹配的所有对象：

    - (NSArray *)historyObjectsContainingQuery:(NSString *)query {
    NSMutableArray *matchingObjects = [[NSMutableArray alloc] init];
    HistoryManager *HM = [HistoryManager sharedInstance];
    for (int i=0; i<[[HM history] count]; i++) {
        //History "days"
        HistoryObject *historyItem = HistoryObject([[HistoryManager sharedInstance] history][i]);

        for (int o=0; o<[historyItem.objects count]; o++) {
            //Each object inn each history day
            HistoryObject *HO = HistoryObject(historyItem.objects[o]);
            if ([HO.title rangeOfString:query options:NSCaseInsensitiveSearch].location != NSNotFound) {
                //history objects with their title containing the query string
                [matchingObjects addObject:HO];
            }
        }
    }
    return matchingObjects;
}

然后我记录每个 url 值：

self.foundInBookmarksAndHistory = [self HistoryObjectsContainingQuery:textField.text]; for (HistoryObject *HO in self.foundInBookmarksAndHistory) { NSLog(@"%@",HO.url); }

这是结果：

https://www.google.com/
2013-09-15 13:48:49.382 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.384 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.385 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.387 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.388 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.390 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.391 Flow HD[3599:60b] https://www.google.com/search?q=yahoo
2013-09-15 13:48:49.392 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.394 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.395 Flow HD[3599:60b] https://www.google.com/search?q=Sup
2013-09-15 13:48:49.397 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.398 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.400 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.402 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.404 Flow HD[3599:60b] https://www.google.com/
2013-09-15 13:48:49.405 Flow HD[3599:60b] https://www.google.com/

还有很多，我如何删除具有相同值的每个对象？这些对象不相等，但具有相等的 url。

我尝试过 NSPredicate 并使用更多的 for 循环来遍历并查找匹配的对象，但我总是留下 2 个或更多具有相同属性的相同对象。

你可以这样做：

NSMutableSet *seenObjects = [NSMutableSet set];
NSPredicate *dupPred = [NSPredicate predicateWithBlock: ^BOOL(id obj, NSDictionary *bind) {
    HistoryObject *hObj = (HistoryObject*)obj;
    BOOL seen = [seenObjects containsObject:hObj.title];
    if (!seen) {
        [seenObjects addObject:hObj.title];
    }
    return !seen;
}];
NSArray *yourHistoryArray = ... // This is your array which needs to be filtered
NSArray *yourHistoryArray = [yourHistoryArray filteredArrayUsingPredicate:dupObjectsPred];