UIImageView 不尊重约束

Question

基本上，我没有将情节提要用于任何事情，而是尝试以编程方式创建这一切。我正在尝试使用 UIImageView 将图像作为横幅放在 UIView 的顶部。图为结果。

白色矩形大约是你看到的两倍长。我将其 contentMode 设置为 scaleAspectFit 并且我认为放大将其推离左侧？当我创建一个标签时它可以正常工作，我只是在使用纵横比进行缩放时遇到这样的问题。

编辑：添加了我的其余课程，因为正如 Evgeniy 指出的那样，这可能是我设置主视图的方式。也许是因为我如何将控制器自身设置为属性中的 mainView？

class MainView:UIView {

override init(frame: CGRect)
{
    super.init(frame: frame)
    self.backgroundColor = .green

    setupViews()
    setupConstraints()
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

func setupViews()
{
    self.addSubview(banner)

    let label = UILabel(frame: self.frame)
    label.text = "HELLO WORLD"

    self.addSubview(label)
    label.translatesAutoresizingMaskIntoConstraints = false
    label.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 0).isActive = true
    label.topAnchor.constraint(equalTo: self.safeAreaLayoutGuide.topAnchor, constant: 10).isActive = true
    label.bottomAnchor.constraint(equalTo: self.safeAreaLayoutGuide.topAnchor, constant: 50).isActive = true
    label.rightAnchor.constraint(equalTo: self.leftAnchor, constant: 100).isActive = true
}

func setupConstraints()
{
    let screenSize:CGRect = UIScreen.main.bounds

    self.translatesAutoresizingMaskIntoConstraints = false
    banner.translatesAutoresizingMaskIntoConstraints = false
    banner.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 0).isActive = true
    banner.topAnchor.constraint(equalTo: self.safeAreaLayoutGuide.topAnchor, constant: 10).isActive = true
    banner.bottomAnchor.constraint(equalTo: self.topAnchor, constant: (screenSize.height/5) + 10).isActive = true
    banner.rightAnchor.constraint(equalTo: self.rightAnchor, constant: 0).isActive = true
}

let banner: UIImageView = {
    let screenSize:CGRect = UIScreen.main.bounds
    let image = UIImage(named: "serveBanner")
    let iView = UIImageView(frame: CGRect(x:0, y:0, width:screenSize.width, height:(screenSize.height/5)))
    iView.clipsToBounds = true
    iView.contentMode = UIView.ContentMode.scaleAspectFit
    iView.image = image
    return iView
}()

}

主视图控制器

import UIKit
class MainViewController: UIViewController {

var mainView:MainView {return self.view as! MainView }
var buttonClicked = false
private let navigator: MainNavigator

init(navigator: MainNavigator)
{
    self.navigator = navigator
    super.init(nibName: nil, bundle: nil)
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

override func loadView()
{
    self.view = MainView(frame: UIScreen.main.bounds)
}

private func buttonAction()
{
    navigator.navigate(to: .PipingSealsApp)
}
}

AppDelegate

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    window = UIWindow(frame: UIScreen.main.bounds)

    let navController = UINavigationController()
    let mainNavigator = MainNavigator(navigationController: navController)
    let mainViewController = MainViewController(navigator: mainNavigator)
    navController.setViewControllers([mainViewController], animated: false)
    window?.rootViewController = navController

    window?.makeKeyAndVisible()

    return true
}

func applicationWillResignActive(_ application: UIApplication) {
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
}

func applicationDidEnterBackground(_ application: UIApplication) {
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

func applicationWillEnterForeground(_ application: UIApplication) {
    // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}

func applicationDidBecomeActive(_ application: UIApplication) {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

func applicationWillTerminate(_ application: UIApplication) {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}
}

Answer 1

所以在挖掘知道它应该可以工作之后，我制作了另一个测试平台并找到了解决方案。这实际上只是一些愚蠢的事情，但人们应该意识到这一点。此代码应删除 self.translatesAutoresizingMaskIntoConstraints = false。

func setupConstraints(){
let screenSize:CGRect = UIScreen.main.bounds

self.translatesAutoresizingMaskIntoConstraints = false
banner.translatesAutoresizingMaskIntoConstraints = false
banner.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 0).isActive = true
banner.topAnchor.constraint(equalTo: self.safeAreaLayoutGuide.topAnchor, constant: 10).isActive = true
banner.bottomAnchor.constraint(equalTo: self.topAnchor, constant: (screenSize.height/5) + 10).isActive = true
banner.rightAnchor.constraint(equalTo: self.rightAnchor, constant: 0).isActive = true
}

应该阅读

func setupConstraints(){
let screenSize:CGRect = UIScreen.main.bounds

banner.translatesAutoresizingMaskIntoConstraints = false
banner.leftAnchor.constraint(equalTo: self.leftAnchor, constant: 0).isActive = true
banner.topAnchor.constraint(equalTo: self.safeAreaLayoutGuide.topAnchor, constant: 10).isActive = true
banner.bottomAnchor.constraint(equalTo: self.topAnchor, constant: (screenSize.height/5) + 10).isActive = true
banner.rightAnchor.constraint(equalTo: self.rightAnchor, constant: 0).isActive = true
}

我不完全确定为什么会发生这种情况，但我会阅读该物业，看看我是否能理解它。感谢大家的帮助！

Answer 2

我试过你的代码没有任何修改（好吧，除了图像名称），得到了这个：

这就是你想要达到的目标吗？ 如果是，那么问题可能在于您如何将主视图添加到视图控制器上？ 这是我的代码，请比较：

let mainView = MainView(frame: self.view.bounds)
mainView.backgroundColor = .green
self.view.addSubview(mainView)

mainView.leftAnchor.constraint(equalTo: self.view.leftAnchor).isActive = true
mainView.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true
mainView.rightAnchor.constraint(equalTo: self.view.rightAnchor).isActive = true
mainView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true