NSPredicate任何及「=無」不工作

Question

這種情況適用

NSPredicate *predicate = [NSPredicate predicateWithFormat: 
     @"ANY region.beacons.major = %d",rangedBeacon.major.intValue]; 

但這並不

NSPredicate *predicate = [NSPredicate predicateWithFormat: 
     @"ANY region.beacons.minor = nil"]; 

信標是區域內對象的列表。主要和次要有型的NSNumber

Answer 1

我找到了解決方案

因爲任何和「=無」不能在相同的條件下（解釋是這裏Core Data, NSPredicate, ANY key.path == nil ）？此問題的解決方案如下所示：

NSPredicate *predicate = [NSPredicate predicateWithFormat: 
     @"SUBQUERY(region.beacons, $x, $x.minor == nil)"]; 

Answer 2

你可以試試這個：

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY region.beacons.minor = $minor"]; 
predicate = [predicate predicateWithSubstitutionVariables: 
[NSDictionary dictionaryWithObject:[NSNull null] forKey: @"minor"]];