记录一下RAC的使用

// 遍历数组内容
    NSArray * array = @[@"1",@"2",@"3",@"4",@"5",@"6"];
    [array.rac_sequence.signal subscribeNext:^(id  _Nullable x) {
        NSLog(@"数组内容：%@", x);
    }];

    // 刷选
    NSArray *filter = [[array.rac_sequence filter:^BOOL(id value) {
        return  [value integerValue] > 2;
    }] array];
    NSLog(@"filter:%@",filter);   // (3,4,5,6)