【发布时间】：2016-02-19 18:30:31
【问题描述】：
我有一个自定义视图 (titleView)，它是为我的 iOS 应用上的 webView 创建的。 titleView 有两个标签，titleLabel 和 subTitleLabel。如果titleLabel 对于titleView 来说太宽，我会截断文本并让它填满整个框架。但只要titleLabel 小于titleView，就会出现问题。当我尝试计算titleLabel 框架的位置时，我得到不一致的结果。我只是假设我会取titelView.frame.size.width 和titleLabel.frame.size.width 的宽度之差除以2，但它不起作用。我可能错过了一些愚蠢的东西，但我只是看不到它。需要注意的一点是subTitleLabel 的定位似乎相当不错，虽然并不完美，但比titleLabel 的位置要好。
这里有一些图像（我在titleView 中添加了边框，它是帮助显示定位的子视图），它们显示了具有不同长度标题字符串的定位：
代码：
UIView *titleView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width - 88, 34)];
titleView.clipsToBounds = YES;
UIFont *titleFont = [UIFont systemFontOfSize:16 weight:UIFontWeightThin];
UIFont *speakerFont = [UIFont systemFontOfSize:10 weight:UIFontWeightLight];
CGSize speakerSize = [[self.speech speakerFullNameAndDate] sizeWithAttributes:@{ NSFontAttributeName : speakerFont }];
CGSize titleSize = [self.speech.title sizeWithAttributes:@{ NSFontAttributeName : titleFont }];
UILabel *titleLabel = [[UILabel alloc] init];
UILabel *subTitleLabel = [[UILabel alloc] init];
[titleView addSubview: titleLabel];
[titleView addSubview:subTitleLabel];
CGFloat titleDifference = (titleView.frame.size.width - titleLabel.frame.size.width) / 2;
titleLabel.text = self.speech.title;
titleLabel.font = titleFont;
titleLabel.textAlignment = NSTextAlignmentCenter;
titleLabel.textColor = [UIColor whiteColor];
titleLabel.backgroundColor = [UIColor clearColor];
titleLabel.lineBreakMode = NSLineBreakByTruncatingTail;
// titleLabel is bigger than the titleView's frame
if (titleSize.width > titleView.frame.size.width) {
titleLabel.frame = CGRectMake(0, 0, titleView.frame.size.width - 20, 18);
} else {
// titleDifference / 3 seems to be the best number for the frame's x coordinate
titleLabel.frame = CGRectMake(titleDifference / 3, 0, titleSize.width, 18);
[titleLabel sizeToFit];
}
subTitleLabel.text = [self.speech speakerFullNameAndDate];
subTitleLabel.font = speakerFont;
subTitleLabel.textAlignment = NSTextAlignmentCenter;
subTitleLabel.textColor = [UIColor whiteColor];
subTitleLabel.backgroundColor = [UIColor clearColor];
// Again, ((titleView.frame.size.width - speakerSize.width) / 3) seems to work best, though it's far from perfect
subTitleLabel.frame = CGRectMake(((titleView.frame.size.width - speakerSize.width) / 3), 20, speakerSize.width, 12);
[subTitleLabel sizeToFit];
self.navigationItem.titleView = titleView;
【问题讨论】：
标签： ios uinavigationcontroller uinavigationitem