Question

我有一个“bookshelf”数组，其中包含四个NSMutableDictionary“book”（其中包含三个属性），我的问题是如何访问“book”字典的hasBeenRead标志/属性以找出哪本书没有读？

书（S）：

 {
     "title":"Winnie-the-Pooh",
     "author":"A.A. Milne"
     "hasBeenRead": No
 }

书架：

[
    {
         "title":"Jungle Book",
         "author":"Rudyard Kipling",
         "hasBeenRead":"Yes"
    },
    {
         "title":"Winnie-the-Pooh",
         "author":"A.A. Milne",
         "hasBeenRead":"No"
    },
    {
         "title":"Alice In Wonderland",
         "author":"Lewis Carroll",
         "hasBeenRead":"Yes"
    }
]

我可以获得Book NSMutableDictionary：

for (NSString* readBook in self.bookshelf) {
    NSLog(@"Books: %@", readBook);
}

感谢。

Answer 1

怎么样：

for (NSDictionary* readBook in self.bookshelf) {
  NSLog(@"Books: %@", [readBook objectForKey:@"hasBeenRead"]);

}

Answer 2

您可以过滤书架使用NSPredicate

NSString *hasBeenReadFlag = @"No";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF.hasBeeRead == %@", hasBeenReadFlag];
NSArray *filtered = [self.bookshelf filteredArrayUsingPredicate:predicate];
NSLog(@"%@", filtered);

现在你可以得到所有书还没有被阅读

此致

如何使用快速枚举访问数组中的NSMutableDictionary属性？

2 个答案: