Swift:内存压力事件 2 vm 0

Question

我在 Xcode 控制台中看到一条消息 Received memory pressure event 1 vm pressure 0 .我不确定是什么原因造成的，为什么但我知道当我在相机 View Controller 中时会打印。我猜这没什么可担心的(还)，但它是否指向我应该尽快修复的问题？

FirstViewController: UIViewController {

    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        let image = info[UIImagePickerController.InfoKey.editedImage] as! UIImage
        let croppedImage = cropToBounds(image: image, width: 10, height: 10)
        self.productImage.image = croppedImage
        print("size: \(croppedImage.size)")
        print("original size: \(image.size)")
        self.dismiss(animated: true, completion: nil)
    }

    func setupCameraPicker() {
        if UIImagePickerController.isSourceTypeAvailable(.camera) {
            let imagePicker = UIImagePickerController()
            imagePicker.delegate = self
            imagePicker.sourceType = .camera;
            imagePicker.allowsEditing = true
            self.present(imagePicker, animated: true, completion: nil)
        }
    }
}

Answer 1

autoreleasepool

autoreleasepool { 
   let image = info[UIImagePickerController.InfoKey.editedImage] as! UIImage
    let croppedImage = cropToBounds(image: image, width: 10, height: 10)
    self.productImage.image = croppedImage
    print("size: \(croppedImage.size)")
    print("original size: \(image.size)")
    self.dismiss(animated: true, completion: nil)
 }

尝试将您的代码放入 autoreleasepool
Foundation 的 NSAutoreleasePool 类型，后来抽象为 @autoreleasepool 块，在 iOS 开发中是一个非常古老的概念。在 iOS 的 Obj-C 时代，这种类型的使用对于防止您的应用程序的内存在特定情况下爆炸很重要。随着 ARC 和 Swift 的出现和发展，很少有人仍然需要手动玩弄内存，这使得看到它变得罕见。