数组筛选

筛选出B数组中不同于A数组中的元素

结果为 arrayB = @[@"d"]

 NSArray *arrayA = @[@"a",@"b",@"c",@"f"];
 NSMutableArray *arrayB =  [NSMutableArray arrayWithObjects:@"a",@"b",@"c",@"d",nil];
 NSPredicate *predicate = [NSPredicate predicateWithFormat:@"NOT (SELF in %@)", arrayA];
 [arrayB filterUsingPredicate:predicate];