使用SnapKit自动调整UILabel的大小

Question

假设CustomView's大小是300x300。 iconImageView有其大小和分配的约束。我不知道UILabel文本会有多长，所以我不想使UILabel的大小保持不变。我的目标是将左约束固定在iconImageView的右侧，将右约束固定在customView。

override func updateConstraints() {
    super.updateConstraints()
    iconImageView.snp.updateConstraints { (make) in
        make.left.equalTo(customView).offset(10)
        make.centerY.equalTo(customView)
        make.size.equalTo(CGSize(width: 40.0, height: 40.0))
    }
    nameLabel.snp.updateConstraints { (make) in
        make.right.equalTo(customView).offset(-10)
        make.left.equalTo(iconImageView.snp.right).offset(10)
        make.centerY.equalTo(customView)
    }
}

当我尝试此方法时，出现错误：Unable to simultaneously satisfy constraints.什么是正确的方法？

Answer 1

好吧，我想您的子视图对顶部/底部约束一无所知，这意味着视图不知道如何重新布局自己。试试这个：

override func updateConstraints() {
    super.updateConstraints()
    iconImageView.snp.updateConstraints { (make) in
        make.left.equalTo(customView).offset(10)
        make.centerY.equalTo(customView)
        // Also from my point of view this line / 
        // is not very readable
        //  make.size.equalTo(CGSize(width: 40.0, height: 40.0))
        // Changed to:
        make.width.height.equalTo(40.0)
    }
    nameLabel.snp.updateConstraints { (make) in
        make.right.equalTo(customView).offset(-10)
        make.left.equalTo(iconImageView.snp.right).offset(10)
        // Add:
        make.top.equalTo(customView.snp.top)
        make.bottom.equalTo(customView.snp.bottom)
    }
}

如果要保持标签的"默认"高度(在空字符串等情况下(，您可以添加：

make.height.greaterThanOrEqual(40.0)

此外，自动布局和框架不能很好地相互配合，因此您应该在"updateConstraint"方法中布局自定义视图，类似于以下内容：

customView.snp.updateConstraints { (make) in 
     make.edges.equalTo(self)
}