NSPredicate与ANY和“= nil”不起作用

Question

此条件有效

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

但这不是

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

信标是区域对象内的列表。主要和次要的类型为NSNumber

Answer 1

你可以试试这个：

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

Answer 2

我找到了解决方案

因为任何和＆＃34; = nil＆＃34;不能处于相同的条件（解释在这里Core Data, NSPredicate, ANY key.path == nil）？解决这个问题的方法如下：

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