本文介绍了确定最后一行的宽度的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有一个包含多行的标签,lineBreakMode设置为UILineBreakModeWordWrap.如何确定最后一行的宽度?
I have a label with multiple lines, lineBreakMode is set to UILineBreakModeWordWrap. How can I determine width of last line?
推荐答案
自iOS 7.0起,您就可以使用此功能来做到这一点(也许您需要根据情况对文本容器进行更多调整):
Since iOS 7.0 you can do it using this function (Maybe you'll have to tweak text container a bit more for your case):
public func lastLineMaxX(message: NSAttributedString, labelWidth: CGFloat) -> CGFloat {
// Create instances of NSLayoutManager, NSTextContainer and NSTextStorage
let labelSize = CGSize(width: bubbleWidth, height: .infinity)
let layoutManager = NSLayoutManager()
let textContainer = NSTextContainer(size: labelSize)
let textStorage = NSTextStorage(attributedString: message)
// Configure layoutManager and textStorage
layoutManager.addTextContainer(textContainer)
textStorage.addLayoutManager(layoutManager)
// Configure textContainer
textContainer.lineFragmentPadding = 0.0
textContainer.lineBreakMode = .byWordWrapping
textContainer.maximumNumberOfLines = 0
let lastGlyphIndex = layoutManager.glyphIndexForCharacter(at: message.length - 1)
let lastLineFragmentRect = layoutManager.lineFragmentUsedRect(forGlyphAt: lastGlyphIndex,
effectiveRange: nil)
return lastLineFragmentRect.maxX
}
Objective-C:
Objective-C:
- (CGFloat)lastLineMaxXWithMessage:(NSAttributedString *)message labelWidth:(CGFloat)labelWidth
{
CGSize labelSize = CGSizeMake(labelWidth, CGFLOAT_MAX);
NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:labelSize];
NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:message];
[layoutManager addTextContainer:textContainer];
[textStorage addLayoutManager:layoutManager];
textContainer.lineFragmentPadding = 0;
textContainer.lineBreakMode = NSLineBreakByWordWrapping;
textContainer.maximumNumberOfLines = 0;
NSUInteger lastGlyphIndex = [layoutManager glyphIndexForCharacterAtIndex:[message length] - 1];
CGRect lastLineFragmentRect = [layoutManager lineFragmentUsedRectForGlyphAtIndex:lastGlyphIndex effectiveRange:nil];
return CGRectGetMaxX(lastLineFragmentRect);
}
然后,您可以确定日期标签的最后一行是否有足够的空间
Then you can decide if there is enough place for your date label in the last line or not
用法示例:
// you definitely have to set at least the font to calculate the result
// maybe for your case you will also have to set other attributes
let attributedText = NSAttributedString(string: label.text,
attributes: [.font: label.font])
let lastLineMaxX = lastLineMaxX(message: attributedText,
labelWidth: label.bounds.width)
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