UIRefreshControl 属性标题多行答案

【问题标题】：UIRefreshControl attributedTitle multiple linesUIRefreshControl 属性标题多行
【发布时间】：2013-04-22 11:33:08
【问题描述】：

是否可以在UIRefreshControl 标题中使用多行？每当我将 \n 添加到 NSAttributedString 时，只会显示第一行。我正在尝试设置标题，并在下一行设置更多文本。那么有没有解决方法在UIRefreshControl 中使用两行文本？

这是当前只显示“Title Here”的代码：

self.refreshControl = [[UIRefreshControl alloc] init];

NSString *title = @"Title Here";
NSString *subText = @"Subtext Here";
NSMutableAttributedString *attString=[[NSMutableAttributedString alloc] initWithString:[NSString stringWithFormat:@"%@\n%@",title,subText]];

[attString addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Helvetica" size:20.0f] range:NSMakeRange(0, [title length])];
[attString addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Helvetica" size:14.0f] range:NSMakeRange([title length],[subText length])];

[attString addAttribute:NSForegroundColorAttributeName value:[UIColor blackColor] range:NSMakeRange(0, [title length])];
[attString addAttribute:NSForegroundColorAttributeName value:[UIColor lightGrayColor] range:NSMakeRange([title length], [subText length])];

self.refreshControl.attributedTitle = attString;

【问题讨论】：

标签： ios objective-c uirefreshcontrol

【解决方案1】：

这里有个棘手的方法：在UIRefreshControl中找到UILabel，设置numberOfLines = 0。

UILabel *titleLabel = [[[[self.refreshControl subviews] firstObject] subviews] lastObject];
if (titleLabel) {
    titleLabel.numberOfLines = 0;

    NSString title = @"Pull to Refresh.\nUpdated Time: 09:30"; // \n for new line.
    self.refreshControl.attributedTitle = [[NSAttributedString alloc] initWithString:title];
}

【讨论】：

【解决方案2】：

这段代码可以工作

NSString *title = @"Title Here";
NSString *subText = @"Subtext Here";

NSMutableAttributedString *titleAttString =  [[NSMutableAttributedString alloc] initWithString:title];
NSMutableAttributedString *subTitleAttString =  [[NSMutableAttributedString alloc] initWithString:subText];

[titleAttString addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Helvetica" size:20.0f] range:NSMakeRange(0, [title length])];
[subTitleAttString addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Helvetica" size:14.0f] range:NSMakeRange(0,[subTitle length])];

[titleAttString addAttribute:NSForegroundColorAttributeName value:[UIColor blackColor] range:NSMakeRange(0, [title length])];
[subTitleAttString addAttribute:NSForegroundColorAttributeName value:[UIColor lightGrayColor] range:NSMakeRange(0, [subTitle length])];

[titleAttString appendAttributedString:subTitleAttString];

self.refreshControl.attributedTitle = titleAttString;

【讨论】：

不起作用，文本彼此相邻显示。有人可以提供正确的答案吗？

【解决方案3】：

诀窍是将刷新控制器的UILable的属性更改为零。 hack 是我们必须通过子视图和子视图找到标签，如下所示。

这是一个 Swift 版本

    if let refreshLabel = refreshControl?.subviews.first?.subviews.last as? UILabel {
            refreshLabel.numberOfLines = 0
    }

这里是完整的代码示例

private var marketRefreshController = UIRefreshControl()
private var lastUpdatedDate = Date()

override func viewDidLoad() {
    super.viewDidLoad()
    tableView.refreshControl = marketRefreshController
    if let refreshLabel = refreshControl?.subviews.first?.subviews.last as? UILabel {
        refreshLabel.numberOfLines = 0
    }
    marketRefreshController.addTarget(self, action: #selector(refreshMarketData), for: .valueChanged)
    marketRefreshController.tintColor = UIColor.blue
    let textAttributes = [NSAttributedString.Key.font: UIFont.appSubTitle,
                          NSAttributedString.Key.foregroundColor: UIColor.blue]
    let timeSinceLastUpdate = lastUpdatedDate.timeAgoSinceNow // Date Sting Converter Helper Method
    let displayString = "Fetching Market Data ... \n Last Updated: \(timeSinceLastUpdate)"
    marketRefreshController.attributedTitle = NSAttributedString(string: displayString,
                                                                 attributes: textAttributes)
    tableView.addSubview(marketRefreshController)
}

预期的输出应该是 -

【讨论】：