Protocol&Delegate練習｜照片編輯App

UIGraphicsImageRenderer, instantiateViewController,UIImagePickerController

🌟APP功能：

・鏡像翻面
・左右翻轉
・更改圖片背景顏色
・儲存圖片

Protocol&Delegate

・UIImagePickerController (以此為例)
・UIColorPickerViewController

轉跳頁面／傳遞資料

・instantiateViewController

儲存 view 為 UIImage 圖片

・UIGraphicsImageRenderer

UIImagePickerController

生出UIImagePickerController，找delegate(代理對象)

//生成選照片的controller，指定delegate(代理對象)
func selectPhoto(sourceType:UIImagePickerController.SourceType) {
        let imageController = UIImagePickerController()
        imageController.sourceType = sourceType
        imageController.delegate = self
        present(imageController, animated: true, completion: nil)
    }

成為delegate(代理對象)必須遵從protocol

Protocol: UIImagePickerControllerDelegate & UINavigationControllerDelegate
定義delegate的function(當使用者選擇照片後，執行該function)

    //定義protocol function
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        let image = info[.originalImage] as? UIImage
        imageView.image = image
        //視窗關閉
        dismiss(animated: true, completion: nil)
}

instantiateViewController

不需在storyboard上建立segue，轉跳至下一頁

欲傳遞資料需使用creator

if let editingViewController = storyboard?.instantiateViewController(identifier: "\(EditingViewController.self)", creator: { coder in EditingViewController.init(coder: coder, image: image!)
            
        }) {
            show(editingViewController, sender: nil)
        }

UIGraphicsImageRenderer

照片編輯完，將UIView的畫面轉為UIImageView。

//產生 UIImageView的尺寸
let renderer = UIGraphicsImageRenderer(size: imageBackgroundView.bounds.size)
        //呼叫image(actions:)產生圖片
        let image = renderer.image(actions: { (context) in
            //從UIView呼叫drawHierarchy(in:afterScreenUpdates:)將 containerView 的內容繪製成圖片
            imageBackgroundView.drawHierarchy(in: imageBackgroundView.bounds, afterScreenUpdates: true)
        })

function image(actions:) 產生圖片

UIActivityViewController 儲存圖片

let activityViewController = UIActivityViewController(activityItems: [image], applicationActivities: nil)
        present(activityViewController, animated: true, completion: nil)

儲存圖片前須設定權限徵求使用者同意，否則將會閃退。.

GitHub

betty-pan/PhotoEditor