NSPredicate测试NULL和空字符串

Question

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)"]; 

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

Answer 1

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

NSPredicate *predicateName = [NSPredicate predicateWithFormat:@"name.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 .

Answer 2

我认为这应该有效：

NSPredicate *predicateName = [NSPredicate predicateWithFormat:@"name!=nil AND name!=''"]; 

Answer 3

 NSPredicate *predicateName = [NSPredicate predicateWithFormat:@"name!=NULL"];

Answer 4

这个谓词对我有用：

[NSPredicate predicateWithFormat:@"(%K== nil) OR %K.length == 0", @"imageUrl", @"imageUrl"]