问题描述
我以前从Parse后端检索图像，使用以下代码行在UIImageView内的应用程序中显示：
I have previously been retrieving an image form my Parse backend to display in my app inside a UIImageView using the following lines of code:
let userPicture = PFUser.currentUser()["picture"] as PFFile
userPicture.getDataInBackgroundWithBlock { (imageData:NSData, error:NSError) -> Void in
if (error == nil) {
self.dpImage.image = UIImage(data:imageData)
}
}
但我收到错误：
有用的Apple修补程序提示建议as！改变所以我添加！，但后来我得到错误：
The 'helpful' Apple fix-it tip suggests the "as!" change so I add in the !, but then I get the error:
使用'getDataInBackgroundWithBlock'部分，我也得到错误：
With the 'getDataInBackgroundWithBlock' section, I also get the error:
有人可以解释如何从Parse正确检索照片并使用 Swift 1.2
Can someone please explain how to correctly retrieve a photo from Parse and display it in a UIImageView using Swift 1.2?
推荐答案
PFUser.currentUser（）返回可选类型（ Self？）。所以你应该通过下标来解包返回值。
PFUser.currentUser() returns optional type (Self?). So you should unwrap return value to access element by subscript.
PFUser.currentUser()?["picture"]
下标得到的值也是可选类型。因此，您应该使用可选绑定来转换值，因为类型转换可能会失败。
And the value got by subscript is also optional type. So you should use optional binding to cast the value because type casting may fail.
if let userPicture = PFUser.currentUser()?["picture"] as? PFFile {
结果块的参数getDataInBackgroundWithBlock（）方法都是可选类型（ NSData？和 NSError？）。所以你应该为参数指定可选类型，而不是 NSData 和 NSError 。
And parameters of the result block of getDataInBackgroundWithBlock() method are both optional type (NSData? and NSError?). So you should specify optional type for the parameters, instead NSData and NSError.
userPicture.getDataInBackgroundWithBlock { (imageData: NSData?, error: NSError?) -> Void in
修改上述所有问题的代码如下：
The code modified the all above problems is below:
if let userPicture = PFUser.currentUser()?["picture"] as? PFFile {
userPicture.getDataInBackgroundWithBlock { (imageData: NSData?, error: NSError?) -> Void in
if (error == nil) {
self.dpImage.image = UIImage(data:imageData)
}
}
}
这篇关于iOS - 从UIImageView中的Parse检索并显示图像（Swift 1.2错误）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！