问题描述

我看过关于右对齐的帖子，但我无法让左对齐工作.我希望按钮占据屏幕的宽度，图像在左侧，标题/文本在中间.

I've seen posts regarding right alignment but I can't get left-alignment to work. I want the button to take up the width of the screen, with the image on the left and the title/text in the center.

这不起作用(至少可靠):

This does not work (at least reliably):

    button.titleLabel.textAlignment = UITextAlignmentCenter;
    [button setImageEdgeInsets:UIEdgeInsetsMake(0, -60.0, 0, 0)];
    button.frame = CGRectMake((self.view.frame.size.width - w ) / 2, self.view.frame.size.height - 140.0,  self.view.frame.size.width - 10.0, 40.0);

推荐答案

此解决方案适用于 Swift 3，并尊重原始内容和图像边缘插入，同时保持标题标签始终位于可用空间的中心，这使得调整边距变得更加容易.

This solution works with Swift 3 and respects original content and image edge insets while keeping the title label always centered in the available space, which makes much easier adjusting margins.

它覆盖 titleRect(forContentRect:) 方法并返回正确的帧:

It overrides titleRect(forContentRect:) method and returns the correct frame:

@IBDesignable
class LeftAlignedIconButton: UIButton {
    override func titleRect(forContentRect contentRect: CGRect) -> CGRect {
        let titleRect = super.titleRect(forContentRect: contentRect)
        let imageSize = currentImage?.size ?? .zero
        let availableWidth = contentRect.width - imageEdgeInsets.right - imageSize.width - titleRect.width
        return titleRect.offsetBy(dx: round(availableWidth / 2), dy: 0)
    }
}

以下插图:

会导致:

不推荐使用之前的答案

这在大多数情况下都有效，但某些布局会导致 layoutSubviews 在无限循环中递归调用自身，因此谨慎使用.

This works in most scenarios, but some layouts cause layoutSubviews to recursively call itself in an endless loop, so use with caution.

@IBDesignable
class LeftAlignedIconButton: UIButton {
    override func layoutSubviews() {
        super.layoutSubviews()
        contentHorizontalAlignment = .left
        let availableSpace = UIEdgeInsetsInsetRect(bounds, contentEdgeInsets)
        let availableWidth = availableSpace.width - imageEdgeInsets.right - (imageView?.frame.width ?? 0) - (titleLabel?.frame.width ?? 0)
        titleEdgeInsets = UIEdgeInsets(top: 0, left: availableWidth / 2, bottom: 0, right: 0)
    }
}

此代码将执行相同的操作，但将图标与右边缘对齐:

This code would do the same but aligning the icon to the right edge:

@IBDesignable
class RightAlignedIconButton: UIButton {
    override func layoutSubviews() {
        super.layoutSubviews()
        semanticContentAttribute = .forceRightToLeft
        contentHorizontalAlignment = .right
        let availableSpace = UIEdgeInsetsInsetRect(bounds, contentEdgeInsets)
        let availableWidth = availableSpace.width - imageEdgeInsets.left - (imageView?.frame.width ?? 0) - (titleLabel?.frame.width ?? 0)
        titleEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: availableWidth / 2)
    }
}

正确的对齐版本使用 semanticContentAttribute 所以它需要 iOS 9+.

The right allignment version uses semanticContentAttribute so it requires iOS 9+.

这篇关于UIButton 上的左对齐图像和居中文本的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！