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];
