我有一个UILabel,它有两行文字的空间。有时,当文本太短时,此文本会显示在标签的垂直中心。
如何垂直对齐文本,使其始终位于UILabel的顶部?
我有一个UILabel,它有两行文字的空间。有时,当文本太短时,此文本会显示在标签的垂直中心。
如何垂直对齐文本,使其始终位于UILabel的顶部?
当前回答
为了防止对任何人都有帮助,我也遇到了同样的问题,但只需从使用UILabel切换到使用UITextView就可以解决这个问题。我很欣赏这并不是每个人都适合的,因为功能有点不同。
如果您切换到使用UITextView,则可以关闭所有滚动视图财产以及启用用户交互。。。这将迫使它更像一个标签。
其他回答
您可以使用TTTAttributedLabel,它支持垂直对齐。
@property (nonatomic) TTTAttributedLabel* label;
<...>
//view's or viewController's init method
_label.verticalAlignment = TTTAttributedLabelVerticalAlignmentTop;
yourLabel.baselineAdjustment = UIBaselineAdjustmentAlignCenters;
子类UILabel并约束绘图矩形,如下所示:
- (void)drawTextInRect:(CGRect)rect
{
CGSize sizeThatFits = [self sizeThatFits:rect.size];
rect.size.height = MIN(rect.size.height, sizeThatFits.height);
[super drawTextInRect:rect];
}
我尝试了涉及换行填充的解决方案,在某些情况下遇到了错误的行为。根据我的经验,如上所述约束绘图矩形比使用numberOfLines更容易。
P.S.你可以想象一下这样轻松地支持UIViewContentMode:
- (void)drawTextInRect:(CGRect)rect
{
CGSize sizeThatFits = [self sizeThatFits:rect.size];
if (self.contentMode == UIViewContentModeTop) {
rect.size.height = MIN(rect.size.height, sizeThatFits.height);
}
else if (self.contentMode == UIViewContentModeBottom) {
rect.origin.y = MAX(0, rect.size.height - sizeThatFits.height);
rect.size.height = MIN(rect.size.height, sizeThatFits.height);
}
[super drawTextInRect:rect];
}
不要大惊小怪
@interface MFTopAlignedLabel : UILabel
@end
@implementation MFTopAlignedLabel
- (void)drawTextInRect:(CGRect) rect
{
NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:self.text attributes:@{NSFontAttributeName:self.font}];
rect.size.height = [attributedText boundingRectWithSize:rect.size
options:NSStringDrawingUsesLineFragmentOrigin
context:nil].size.height;
if (self.numberOfLines != 0) {
rect.size.height = MIN(rect.size.height, self.numberOfLines * self.font.lineHeight);
}
[super drawTextInRect:rect];
}
@end
没有混乱,没有Objective-c,没有大惊小怪,只有Swift 3:
class VerticalTopAlignLabel: UILabel {
override func drawText(in rect:CGRect) {
guard let labelText = text else { return super.drawText(in: rect) }
let attributedText = NSAttributedString(string: labelText, attributes: [NSFontAttributeName: font])
var newRect = rect
newRect.size.height = attributedText.boundingRect(with: rect.size, options: .usesLineFragmentOrigin, context: nil).size.height
if numberOfLines != 0 {
newRect.size.height = min(newRect.size.height, CGFloat(numberOfLines) * font.lineHeight)
}
super.drawText(in: newRect)
}
}
雨燕4.2
class VerticalTopAlignLabel: UILabel {
override func drawText(in rect:CGRect) {
guard let labelText = text else { return super.drawText(in: rect) }
let attributedText = NSAttributedString(string: labelText, attributes: [NSAttributedString.Key.font: font])
var newRect = rect
newRect.size.height = attributedText.boundingRect(with: rect.size, options: .usesLineFragmentOrigin, context: nil).size.height
if numberOfLines != 0 {
newRect.size.height = min(newRect.size.height, CGFloat(numberOfLines) * font.lineHeight)
}
super.drawText(in: newRect)
}
}
雨燕5
这里是从左上角开始渲染文本,并保持可能调整的文本大小。
final class TopAlignedLabel: UILabel {
override func drawText(in rect: CGRect) {
super.drawText(in: .init(
origin: .zero,
size: textRect(
forBounds: rect,
limitedToNumberOfLines: numberOfLines
).size
))
}
}