ImageView不会使用新图像进行更新
ImageView不会使用新图像进行更新
提问于 2017-03-10 03:23:53
我正在尝试从用户的手机中选择一个图像，并使用所述图像更新图像视图。
我遇到的问题是它不会更新图像。当我添加断点并命中断点时，它确实到达了那里，并且图像视图可以更改图像，因为我尝试在其他地方手动更改它。
但是当我需要它的时候，它却拒绝工作。
我的图片视图：
lazy var profilePictureImageView: UIImageView = {
let imageView = UIImageView()
imageView.image = UIImage(named: "DefaultUser")
imageView.translatesAutoresizingMaskIntoConstraints = false
imageView.contentMode = .scaleAspectFill
imageView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleSelectProfilePicture)))
imageView.isUserInteractionEnabled = true
return imageView
}()通过在设备上选择一张照片来更新图像的代码：
import UIKit
extension ProfileVC: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
func handleSelectProfilePicture() {
let picker = UIImagePickerController()
picker.delegate = self
picker.allowsEditing = true
present(picker, animated: true, completion: nil)
}
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
var selectedImageFromPicker: UIImage?
if let editedImage = info["UIImagePickerControllerEditedImage"] as? UIImage {
selectedImageFromPicker = editedImage
}
else if let originalImage = info["UIImagePickerControllerOriginalImage"] as? UIImage {
selectedImageFromPicker = originalImage
}
if let selectedImage = selectedImageFromPicker {
profilePictureImageView.image = selectedImage
}
dismiss(animated: true, completion: nil)
}
func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
dismiss(animated: true, completion: nil)
}
}编辑我发现的一件事是，如果我在不同的VC上用不同的图像视图尝试它，它会像预期的那样工作。我能看到的两个VC之间唯一的主要区别是我希望它能工作，但不会同时扩展'UIPickerViewDelegate‘和'UIPickerViewDataSource’。会有冲突吗？
回答 6
Stack Overflow用户
回答已采纳
发布于 2017-05-10 09:09:22
试试这个，它对我很有效：
DispatchQueue.main.async {
profilePictureImageView.image = croppedImage
profilePictureImageView.setNeedsDisplay()
}本质上，您需要指定您想要通过
profilePictureImageView.setNeedsDisplay()Stack Overflow用户
发布于 2017-03-10 04:03:40
您希望在主线程上执行所有UI更新，例如更改图像：
if let selectedImage = selectedImageFromPicker {
DispatchQueue.main.async {
profilePictureImageView.image = selectedImage
}
}应该做这件事。
Stack Overflow用户
发布于 2017-03-10 05:21:26
我对这段代码没有任何问题，我已经尽可能地复制了你的代码。
class ViewController: UIViewController {
lazy var imageView: UIImageView = {
let iView = UIImageView()
iView.contentMode = .scaleAspectFill
iView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleSelectProfilePicture)))
iView.isUserInteractionEnabled = true
return iView
}()
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(imageView)
self.imageView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint(item: imageView, attribute: .height, relatedBy: .equal, toItem: self.view, attribute: .height, multiplier: 1.0, constant: 1.0).isActive = true
NSLayoutConstraint(item: imageView, attribute: .width, relatedBy: .equal, toItem: self.view, attribute: .width, multiplier: 1.0, constant: 1.0).isActive = true
}
func handleSelectProfilePicture() {
let picker = UIImagePickerController()
picker.delegate = self
picker.allowsEditing = true
present(picker, animated: true, completion: nil)
}
}
extension ViewController: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
var selectedImageFromPicker: UIImage?
if let editedImage = info["UIImagePickerControllerEditedImage"] as? UIImage {
selectedImageFromPicker = editedImage
}
else if let originalImage = info["UIImagePickerControllerOriginalImage"] as? UIImage {
selectedImageFromPicker = originalImage
}
if let selectedImage = selectedImageFromPicker {
imageView.image = selectedImage
}
dismiss(animated: true, completion: nil)
}
func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
dismiss(animated: true, completion: nil)
}
}这个问题一定是由代码中的其他东西引起的。我使用了一个和你一样的lazy变量。你能不能试着简化你的代码，看看它是否能工作，或者发布剩下的代码。您设置了哪些限制条件？
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/42703795
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