NSPredicate测试NULL和空白字符串 [英] NSPredicate to test for NULL, and blank strings

问题描述

我有一个NSArray，需要过滤掉所有为null或具有''(空字符串)的字符串.我怎么做?我已经尝试过:

I have an NSArray and need to filter out any strings that are null or rather, have ' ' (empty string). How do I do that? I have tried doing:

NSPredicate *predicateName = [NSPredicate predicateWithFormat:@"(name!=nil)"]; 

但是似乎不起作用.也许可以，但是有不同类型的null ...

but that doesn't seem to work. Or maybe it does but there are different kinds of null...

推荐答案

如果您不使用Core Data，则可以执行以下操作:

If you don't use Core Data, you could do:

NSPredicate *predicateName = [NSPredicate predicateWithFormat:@"name.length > 0"];

如果字符串为空，则会失败(因为0 == 0).同样，如果name为nil，则也会失败，因为[nil length] == 0.

If the string is empty, this will fail (because 0 == 0). Similarly, if name is nil, it will also fail, because [nil length] == 0.

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