iOS AutoLayout使用技巧

关于ContentCompressionResistance， ContentHugging运用

如下图效果图，两个Label并列在同一排上，左边label自适应，右边label（红色）要使得内容全部展示，如果左边label内容很少，那么右边label随着左边label动。

使用Snapkit 约束实现效果

使用xib AutoLayout 约束实现效果

xib AutoLayout关键设置

1.设置好相关约束，详见demo.

2.把左边label Compression horizontal降低至250（默认750，设置低于750任意值均可），右边红色label无需修改。

如下图

Snapkit 约束关键代码

import UIKit
import SnapKitclass SnpTableViewCell: UITableViewCell {var placeLabel = UILabel()var distanceLabel = UILabel()override init(style: UITableViewCellStyle, reuseIdentifier: String?) {super.init(style: style, reuseIdentifier: reuseIdentifier)setupUI()}required init?(coder aDecoder: NSCoder) {fatalError("init(coder:) has not been implemented")}override func awakeFromNib() {super.awakeFromNib()}/// MARK: -setup UIfunc setupUI() {distanceLabel.textColor = UIColor.redif #available(iOS 8.2, *) {distanceLabel.font = UIFont.systemFont(ofSize: 17, weight: UIFont.Weight.semibold)} else {distanceLabel.font = UIFont.boldSystemFont(ofSize: 17)}contentView.addSubview(placeLabel)contentView.addSubview(distanceLabel)placeLabel.snp.makeConstraints {$0.left.equalToSuperview().offset(16)$0.top.bottom.equalToSuperview()}distanceLabel.snp.makeConstraints{$0.top.bottom.equalToSuperview()$0.left.equalTo(placeLabel.snp.right).offset(32)$0.right.lessThanOrEqualToSuperview().offset(-16)}//set CompressionResistance  ContentHuggingdistanceLabel.setContentCompressionResistancePriority(.required, for: .horizontal)distanceLabel.setContentHuggingPriority(.required, for: .horizontal)placeLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)placeLabel.setContentHuggingPriority(.required, for: .horizontal)}override func setSelected(_ selected: Bool, animated: Bool) {super.setSelected(selected, animated: animated)// Configure the view for the selected state}}
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关键设置代码是：

   //set CompressionResistance  ContentHuggingdistanceLabel.setContentCompressionResistancePriority(.required, for: .horizontal)distanceLabel.setContentHuggingPriority(.required, for: .horizontal)placeLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)placeLabel.setContentHuggingPriority(.required, for: .horizontal)
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