Swift 重构：通过预设视图样式，缩减代码量

通过预设常用视图基础属性，缩减每次创建时需要声明的属性行数（之后创建时不需要再重复声明），项目越大收益越高；

🌰🌰：

{
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    UIApplication.setupAppearance(.white, barTintColor: .systemBlue)
}

源码：

@objc public extension UIApplication{

    /// 配置 app 外观主题色
    static func setupAppearance(_ tintColor: UIColor, barTintColor: UIColor) {
        _ = {
            $0.barTintColor = barTintColor
            $0.tintColor = tintColor
            $0.titleTextAttributes = [NSAttributedString.Key.foregroundColor: tintColor,]
          }(UINavigationBar.appearance())
        
        
        _ = {
            $0.setTitleTextAttributes([NSAttributedString.Key.foregroundColor: UIColor.black], for: .normal)
          }(UIBarButtonItem.appearance(whenContainedInInstancesOf: [UIImagePickerController.self]))


        _ = {
            $0.setTitleColor(tintColor, for: .normal)
            $0.titleLabel?.adjustsFontSizeToFitWidth = true;
            $0.titleLabel?.minimumScaleFactor = 1.0;
            $0.imageView?.contentMode = .scaleAspectFit
            $0.isExclusiveTouch = true
            $0.adjustsImageWhenHighlighted = false
          }(UIButton.appearance(whenContainedInInstancesOf: [UINavigationBar.self]))
        
        
        _ = {
            $0.tintColor = tintColor

            $0.setTitleTextAttributes([NSAttributedString.Key.foregroundColor: tintColor,
            ], for: .normal)
            $0.setTitleTextAttributes([NSAttributedString.Key.foregroundColor: barTintColor,
            ], for: .selected)
          }(UISegmentedControl.appearance(whenContainedInInstancesOf: [UINavigationBar.self]))

        
        _ = {
            $0.tintColor = tintColor
          }(UISegmentedControl.appearance())
        
        
        _ = {
            $0.autoresizingMask = [.flexibleWidth, .flexibleHeight]
            $0.showsHorizontalScrollIndicator = false
            $0.keyboardDismissMode = .onDrag;
            if #available(iOS 11.0, *) {
                $0.contentInsetAdjustmentBehavior = .never;
            }
          }(UIScrollView.appearance())
        
        
        _ = {
            $0.separatorInset = .zero
            $0.separatorStyle = .singleLine
            $0.rowHeight = 60
            $0.backgroundColor = .groupTableViewBackground
            if #available(iOS 11.0, *) {
                $0.estimatedRowHeight = 0.0;
                $0.estimatedSectionHeaderHeight = 0.0;
                $0.estimatedSectionFooterHeight = 0.0;
            }
          }(UITableView.appearance())
        

        _ = {
            $0.layoutMargins = .zero
            $0.separatorInset = .zero
            $0.selectionStyle = .none
            $0.backgroundColor = .white
          }(UITableViewCell.appearance())

        
        _ = {
            $0.scrollsToTop = false
            $0.isPagingEnabled = true
            $0.bounces = false
          }(UICollectionView.appearance())
        
        
        _ = {
            $0.layoutMargins = .zero
            $0.backgroundColor = .white
          }(UICollectionViewCell.appearance())
        
        
        _ = {
            $0.titleLabel?.adjustsFontSizeToFitWidth = true;
            $0.titleLabel?.minimumScaleFactor = 1.0;
            $0.imageView?.contentMode = .scaleAspectFit
            $0.isExclusiveTouch = true
            $0.adjustsImageWhenHighlighted = false
          }(UIButton.appearance())
        
        
        _ = {
            $0.isUserInteractionEnabled = true;
          }(UIImageView.appearance())
        
        
        _ = {
            $0.isUserInteractionEnabled = true;
          }(UILabel.appearance())
        
        
        _ = {
            $0.pageIndicatorTintColor = barTintColor
            $0.currentPageIndicatorTintColor = tintColor
            $0.isUserInteractionEnabled = true;
            $0.hidesForSinglePage = true;
          }(UIPageControl.appearance())
        
        
        _ = {
            $0.progressTintColor = barTintColor
            $0.trackTintColor = .clear
          }(UIProgressView.appearance())
        
        
        _ = {
            $0.datePickerMode = .date;
            $0.locale = Locale(identifier: "zh_CN");
            $0.backgroundColor = .white;
            if #available(iOS 13.4, *) {
                $0.preferredDatePickerStyle = .wheels
            }
          }(UIDatePicker.appearance())
        
        
        _ = {
            $0.minimumTrackTintColor = tintColor
            $0.autoresizingMask = .flexibleWidth
          }(UISlider.appearance())
        
        
        _ = {
            $0.onTintColor = tintColor
            $0.autoresizingMask = .flexibleWidth
          }(UISwitch.appearance())
        
    }
}