MJRefresh - tableView.mj_header

 MJRefreshNormalHeader *header = [MJRefreshNormalHeader headerWithRefreshingBlock:^{
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
                [weakSelf.tableView.mj_header endRefreshing];
            });
        }];

        // 修改文字
        [header setTitle:@"正在搜索设备" forState:MJRefreshStateIdle];
        [header setTitle:@"正在搜索设备" forState:MJRefreshStatePulling];
        [header setTitle:@"正在搜索设备" forState:MJRefreshStateRefreshing];

        // 设置状态文字
        [header setTitle:@"下拉可以刷新了～" forState:MJRefreshStateIdle];
        [header setTitle:@"松开立即刷新哦～" forState:MJRefreshStatePulling];
        [header setTitle:@"正在刷新中，请稍候..." forState:MJRefreshStateRefreshing];

        // 修改字体和颜色
        header.stateLabel.font = [UIFont systemFontOfSize:14];
        header.stateLabel.textColor = UIColorMakeWithHex(@"#E21C34");

        header.lastUpdatedTimeLabel.font = [UIFont systemFontOfSize:14];
        header.lastUpdatedTimeLabel.textColor = UIColorMakeWithHex(@"#E21C34");

        header.lastUpdatedTimeLabel.hidden = YES;
        
        // 修改 activity indicator 颜色为红色
        UIActivityIndicatorView *indicator = (UIActivityIndicatorView *)[header valueForKey:@"loadingView"];
        indicator.color = UIColorMakeWithHex(@"#E21C34");

        // 设置到 tableView
        _tableView.mj_header = header;