iOS 小技巧的整理

设置按钮图片高度

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()

        let btHeight: CGFloat = 100
        let demoButton = UIButton(type: .custom)
        demoButton.frame.size = CGSize(width: 50, height: btHeight)
        demoButton.setImage(UIImage(named: "img"), for: .normal)
        demoButton.setImageHeight(20, buttonHeight: btHeight)
        view.addSubview(demoButton)
        
    }

}

extension UIButton {
    
    func setImageHeight(_ height: CGFloat, buttonHeight: CGFloat) {
        // 如果不满足 buttonHeight >= height， 则报错
        assert(buttonHeight >= height, "图片高度大于按钮高度！请重新设置")
        assert(height > 0 && buttonHeight > 0, "高度必须大于0")

        let gap = (buttonHeight-height)/2
        imageView?.contentMode = .scaleAspectFit
        imageEdgeInsets = UIEdgeInsets(top: gap, left: 0, bottom: gap, right: 0)
    }
}

UINavigationController 自定义了 navigationItem.leftBarButtonItem 的滑动返回

在 UINavigationController 中，如果 A push B， B 中自定义了 navigationItem.leftBarButtonItem

    // In B viewcontrcolleer
    override func viewDidLoad() {
        super.viewDidLoad()
        
        navigationItem.leftBarButtonItem = UIBarButtonItem(title: "XXOO", style: .plain, target: self, action: #selector(backTest))
    }

那么此时在该页面的UINavigationController滑动返回是不起作用的，设置self.navigationController?.interactivePopGestureRecognizer?.delegate = self 即可正常滑动返回了

    // In B viewcontrcolleer
    override func viewDidLoad() {
        super.viewDidLoad()
        
        navigationItem.leftBarButtonItem = UIBarButtonItem(title: "XXOO", style: .plain, target: self, action: #selector(backTest))
        self.navigationController?.interactivePopGestureRecognizer?.delegate = self
    }

UINavigationBar 去除默认分割线

extension UINavigationBar {
    
    // 去除 UINavigationBar 默认分割线
    func setWithNoSeperateLine() {
        self.setBackgroundImage(UIImage.from(color: UIColor.clear), for: .any, barMetrics: .default)
        self.shadowImage = UIImage()
    }
    
    // 使用 UINavigationBar 默认分割线
    func setWithDefaultBar() {
        self.setBackgroundImage(nil, for: .any, barMetrics: .default)
        self.shadowImage = nil
    }

}