使用 NSPredicate 过滤 NSArray 和 2D-​​NSDictionaries

Question

我有一个NSArray，其中包含一些NSDictionaries，它们本身也包含一个NSDictionary。

NSDictionary *dict1 = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:@"cover" forKey:@"type"] forKey:@"image"];
NSDictionary *dict2 = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:@"cover" forKey:@"type"] forKey:@"image"];
NSDictionary *dict3 = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:@"back" forKey:@"type"] forKey:@"image"];
NSDictionary *dict4 = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:@"cover" forKey:@"type"] forKey:@"image"];

NSArray *myArray = [NSArray arrayWithObjects:dict1, dict2, dict3, dict4, nil];

有没有办法为类型为 f.e. 的所有图像词典过滤 myArray。使用 NSPredicate 来“覆盖”？

尝试过像

这样的谓词

predicateWithFormat:@"(SELF.image.type == %@)", @"cover"]

或

predicateWithFormat:@"(image.type == %@)", @"cover"]

但没有成功。

提前致谢！如果有不清楚的地方请发表评论

// 编辑

所以

NSPredicate *p = [NSPredicate predicateWithFormat:@"image.type == %@", @"cover"];

正在工作。但就我而言，我想整理尺寸==原始。我所做的是

NSPredicate *p = [NSPredicate predicateWithFormat:@"image.size == %@", @"original"];

然后我的应用程序崩溃了

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSSymbolicExpression length]: unrecognized selector sent to instance

并指向我的filteredArrayUsingPredicate 方法。我看不出类型和大小之间有什么区别。在这里查看我的数组的 NSLog

 (
        {
        image =         {
            height = 1500;
            id = 4e5808765e73d607350059b4;
            size = original;
            type = poster;
            url = "someurl";
            width = 1000;
        };
    },
        {
        image =         {
            height = 750;
            id = 4e5808765e73d607350059b4;
            size = mid;
            type = poster;
            url = "someurl";
            width = 500;
        };
    },

有人知道为什么当我尝试使用大小而不是类型时它会崩溃吗？

Answer 1

SIZE 是保留关键字。

在Predicate Programming Guide的底部找到：

以下词语保留：

AND, OR, IN, NOT, ALL, ANY, SOME, NONE, LIKE, CASEINSENSITIVE, CI, MATCHES, CONTAINS, BEGINSWITH, ENDSWITH, BETWEEN, NULL, NIL, SELF, TRUE, YES, FALSE, NO, FIRST , LAST, SIZE, ANYKEY, 子查询, CAST, TRUEPREDICATE, FALSEPREDICATE

Answer 2

以下代码对我有用：

NSDictionary *dict1 = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:@"cover" forKey:@"type"] forKey:@"image"];
NSDictionary *dict2 = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:@"cover" forKey:@"type"] forKey:@"image"];
NSDictionary *dict3 = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:@"back" forKey:@"type"] forKey:@"image"];
NSDictionary *dict4 = [NSDictionary dictionaryWithObject:[NSDictionary dictionaryWithObject:@"cover" forKey:@"type"] forKey:@"image"];

NSArray *myArray = [NSArray arrayWithObjects:dict1, dict2, dict3, dict4, nil];

NSPredicate *p = [NSPredicate predicateWithFormat:@"image.type == %@", @"cover"];
NSLog(@"%@", [myArray filteredArrayUsingPredicate:p]);