AutoLayout与UIbutton

1、UIButton贴近右边，高度固定，宽度跟随标题变化

class TestButton: UIButton {
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        let btn = TestButton(type: .custom)
        btn.setTitle("TestButton 1 2 3 sdasdad dadasd", for: .normal)
        btn.setTitleColor(.black, for: .normal)
        btn.layer.borderColor = UIColor.red.cgColor
        btn.layer.borderWidth = 1
        view.addSubview(btn)

        btn.snp.makeConstraints { (make) in
            make.centerY.equalToSuperview()
            make.right.equalToSuperview().offset(-20)
            make.height.equalTo(30)
        }
    }
}

　　效果：

2、限制宽度，多了就换行

class TestButton: UIButton {
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        let btn = TestButton(type: .custom)
        btn.setTitle("TestButton 1 2 3 sdasdad dadasd,TestButton 1 2 3 sdasdad dadasd,TestButton 1 2 3 sdasdad dadasd", for: .normal)
        btn.setTitleColor(.black, for: .normal)
        btn.titleLabel?.numberOfLines = 0
        btn.layer.borderColor = UIColor.red.cgColor
        btn.layer.borderWidth = 1
        view.addSubview(btn)

        btn.snp.makeConstraints { (make) in
            make.centerY.equalToSuperview()
            make.right.equalToSuperview().offset(-20)
//            make.height.equalTo(30)
            make.width.lessThanOrEqualTo(200)
        }
    }
}

　　效果：

 明显，UIButton的框太小了，限制了titleLabel，现在想实现，button的高度和文字高度一样

修改如下

class TestButton: UIButton {
    override var intrinsicContentSize: CGSize {
        return titleLabel!.sizeThatFits(CGSize( titleLabel!.preferredMaxLayoutWidth, height: .greatestFiniteMagnitude))
    }
    override func layoutSubviews() {
        titleLabel?.preferredMaxLayoutWidth = frame.size.width
        super.layoutSubviews()
    }
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        let btn = TestButton(type: .custom)
        btn.setTitle("TestButton 1 2 3 sdasdad dadasd,TestButton 1 2 3 sdasdad dadasd,TestButton 1 2 3 sdasdad dadasd", for: .normal)
        btn.setTitleColor(.black, for: .normal)
        btn.titleLabel?.numberOfLines = 0
        btn.layer.borderColor = UIColor.red.cgColor
        btn.layer.borderWidth = 1
        view.addSubview(btn)

        btn.snp.makeConstraints { (make) in
            make.centerY.equalToSuperview()
            make.right.equalToSuperview().offset(-20)
//            make.height.equalTo(30)
            make.width.lessThanOrEqualTo(200)
        }
    }
}

　　效果：

总结：

Autolayout和intrinsicContentSize有关，UIButton的intrinsicContentSize默认和标题长短没有关系，和UILabel不一样