leetcode 26 删除数组重复元素 oc Object-C

    {
        NSArray *arr = @[@"0",@"0",@"1",@"1",@"1",@"2",@"2",@"3",@"3",@"4"];

        NSMutableDictionary *dic = [[NSMutableDictionary alloc] init];
        
        [arr enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
            [dic setObject:@"" forKey:obj];
        }];
        
        NSMutableArray *keys = [dic allKeys].mutableCopy;
        
        [keys sortUsingSelector:@selector(compare:)];
        
        NSLog(@"%@",keys);
    
    }