ios - 如何在保存到 PNG 的 Swift 中的 .WriteToFile 的图像顶部插入标签

Question

我正在尝试使用 .WriteToFile 在图像顶部保存标签。

这是我用来保存图像的代码:

    let selectedImage: UIImage = image.image!
     let fileManager = NSFileManager.defaultManager()
     let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as String
     let filePathToWrite = "\(paths)/User_Profile_Image.png"
     let imageData: NSData = UIImagePNGRepresentation(selectedImage)!
     let jpgImageData = UIImageJPEGRepresentation(selectedImage, 1.0)
     fileManager.createFileAtPath(filePathToWrite, contents: jpgImageData, attributes: nil)
     // Check file saved successfully        
      let getImagePath = (paths as NSString).stringByAppendingPathComponent("User_Profile_Image.png")
     if (fileManager.fileExistsAtPath(getImagePath)) {
     print("FILE AVAILABLE");
  } else {
     print("FILE NOT AVAILABLE");
 }

但它只保存图像:

我正在尝试通过以下方式检索它:

 if let pdfURL = NSBundle.mainBundle().URLForResource("User_Profile_Image", withExtension: "png", subdirectory: nil, localization: nil),data = NSData(contentsOfURL: pdfURL), baseURL = pdfURL.URLByDeletingLastPathComponent  {
       let webView = UIWebView(frame: CGRectMake(20,20,self.view.frame.size.width-40,self.view.frame.size.height-40))
    print("Hello World")
    webView.loadData(data, MIMEType: "application/pdf", textEncodingName:"", baseURL: baseURL)//application/
    self.view.addSubview(webView)
  }

但它不起作用。有什么想法吗？

Answer 1

在您当前的方法中，您将 UILabel 放置在图像的顶部，这不会以任何方式修改图像，标签只是位于图像上方。要在图像上实际写入文本，您需要使用 Graphics 上下文在图像上实际绘制文本。

看看下面的代码，这将拍摄一张图片并在右下角用白色文本写下 Hello World。

class ViewController: UIViewController {

    @IBOutlet weak var imageVIew: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.


    }

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)

        let font = UIFont.boldSystemFontOfSize(30)
        let showText:NSString = "hello world"
        // setting attr: font name, color...etc.
        let attr = [NSFontAttributeName: font, NSForegroundColorAttributeName:UIColor.whiteColor()]
        // getting size
        let sizeOfText = showText.sizeWithAttributes(attr)

        let image = UIImage(named: "dog")
        let rect = CGRectMake(0, 0, image!.size.width, image!.size.height)

        UIGraphicsBeginImageContextWithOptions(CGSize(width: rect.size.width, height: rect.size.height), true, 0)

        // drawing our image to the graphics context
        image?.drawInRect(rect)
        // drawing text
        showText.drawInRect(CGRectMake(rect.size.width-sizeOfText.width-10, rect.size.height-sizeOfText.height-10, rect.size.width, rect.size.height), withAttributes: attr)

        // getting an image from it
        let newImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext()

        self.imageVIew.image = newImage
    }
}

完成此操作后，您可以将新图像另存为文件，或覆盖现有图像。

我用了这个guide的底部作为引用，我已经有一段时间没有做这样的事情了