使用NSPredicate检测NOT CONTAINS [英] Use an NSPredicate to detect NOT CONTAINS

问题描述

我放弃了。我试过每一个组合，我可以想象，以检查一个字符串是否包含另一个字符串。下面是一个描述我想要做的直观语法的例子：

I give up. I have tried every combination I can imagine to check if a string contains another string. Here's an example of intuitive syntax describing what I want to do:

    NSPredicate* pPredicate = [NSPredicate predicateWithFormat:@"NOT (%K CONTAINS[c] %@)",
NSMetadataItemFSNameKey, 
[NSString stringWithFormat:@"Some String"]];

无论我如何移动NOT，

Regardless of how I shift the NOT around, use the ! operator instead, shift the parentheses or remove them altogether, I always get an exception parsing this expression.

这个表达式有什么问题？

What is wrong with this expression?

编辑：当我调用

[pMetadataQuery setPredicate:pPredicate];

，例外情况是： * 由于未捕获异常而终止应用程序'NSInvalidArgumentException '，reason：'未知类型的NSComparisonPredicate给予NSMetadataQuery（kMDItemFSName CONTAINS [c]Some String）'

and the exception is: * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unknown type of NSComparisonPredicate given to NSMetadataQuery (kMDItemFSName CONTAINS[c] "Some String")'

推荐答案

I完全成功：

NSPredicate* predicate = [NSPredicate predicateWithFormat:@"NOT (%K CONTAINS[c] %@)",
        @"someKey",
        [NSString stringWithFormat:@"Some String"]];
NSArray *testArray =
    [NSArray arrayWithObjects:
        [NSDictionary dictionaryWithObject:@"This sure is Some String" forKey:@"someKey"],
        [NSDictionary dictionaryWithObject:@"I've nothing to say" forKey:@"someKey"],
        [NSDictionary dictionaryWithObject:@"I don't even have that key" forKey:@"someOtherKey"],
        nil];

NSArray *filteredArray = [testArray filteredArrayUsingPredicate:predicate];
NSLog(@"found %@", filteredArray);

testArray 结束于 filteredArray ，在OS X v10.7和iOS v4.3下。所以问题不是谓词 - 使这在技术上是一个完整的答案的问题 - 这是一种限制在 NSMetadataQuery 。可悲的是，我没有在这方面的经验，但它肯定是下一步研究。

The second two objects of the three in testArray ended up in filteredArray, under OS X v10.7 and iOS v4.3. So the issue isn't the predicate — making this technically a complete answer to the question — it's some sort of restriction in NSMetadataQuery. Sadly I've no experience in that area, but it's certainly the next thing to research.

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