在swift中通过inout参数编写一个var

Posted 2023-02-24

【中文标题】在swift中通过inout参数编写一个var

【英文标题】：Writing a var via inout parameter in swift

【发布时间】：2015-01-05 09:54:50

【问题描述】：

我想将几张图片加载到一个模型中。我正在尝试使用 loadImage() 函数和 inout 参数来解决这个问题。但由于某种原因，图像变量始终为空。我没有看到图像。

这里有什么问题？

   public var image: UIImage = UIImage()

   // Somewhere in the init function 
   self.loadImage("http://www.domain.com/cats.img", targetImage: &self.image)

   func loadImage(url:String, inout targetImage:UIImage) 
        dispatch_group_enter(self.dispatch_group);

        println("Start loading image \(url)")

        var request:Alamofire.Request = Alamofire.request(.GET, url).responseImage() 
            (request, _, image, error) in
            if error == nil && image != nil 
                println("imageRequestSuccess")

                // Save the image to the model property
                targetImage = image!

                // Dispatch if success
                dispatch_group_leave(self.dispatch_group)
             else 
                println("imageRequestFailure")

                // Dispatch also to handle failure
                dispatch_group_leave(self.dispatch_group)
            
        
    

【参考方案1】：

使用闭包效果很好......但看起来很难看

self.loadImage(self.image_url!, onSuccess:  s1 in return self.image = s1 )



    func loadImage(url:String, onSuccess: (s1:UIImage) -> () ) 
        dispatch_group_enter(self.dispatch_group);

        println("Start loading image \(url)")

        var request:Alamofire.Request = Alamofire.request(.GET, url).responseImage() 
            (request, _, image, error) in
            if error == nil && image != nil 
                println("imageRequestSuccess")

                onSuccess(s1:image!)

                // Dispatch if success
                dispatch_group_leave(self.dispatch_group)
             else 
                println("imageRequestFailure")

                // Dispatch also to handle failure
                dispatch_group_leave(self.dispatch_group)