将0作为枚举选项传递给Swift中的Objective C函数 [英] Passing 0 as an enum option into Objective C functions in Swift

问题描述

有一些Objective-C库具有整数枚举选项作为参数的函数，但是如果您希望使用默认选项，那么它们希望通过0。但是在Swift中，这是不允许的，因为库指定枚举类型。有没有办法在这个简单的添加一个0枚举选项到库，然后使桥接代码使其ObjC枚举在Swift工作？

这里有一个例子，$在iPhone应用程序中的c $ c> SDWebImageManager

  SDWebImageManager.sharedManager（）。downloadWithURL（url ，options：0，progress：nil）{（image：UIImage !, error：NSError !, cacheType：SDImageCacheType，finished：Bool） - > 
 //块中的代码
} 
  

Xcode将指出选项：0 的错误，因为'Int'不能转换为SDWebImageOptions 。我已经尝试过类似以下内容，但是我收到相同的错误：

  let emptyOptions：SDWebImageOptions = 0 
  

解决方案

从Swift 2起，选项集的语法已更改为使用数组文字。所以如果你想传递任何选项，你传递一个空列表：

  SDWebImageManager.sharedManager（）。downloadWithURL（url，options ：[]，progress：nil）{（image：UIImage !, error：NSError !, cacheType：SDImageCacheType，finished：Bool） - >空虚
 //这里的代码
} 
  

There are Objective-C libraries with functions that take integer enum options as a parameter, but they expect you to pass 0 in if you want default options, as is typical. But in Swift, that is not allowed because the library specifies an enum type. Is there any way around this short of adding a 0 enum option to the libraries then making bridging code to make its ObjC enums work in Swift?

Here's an example with SDWebImageManager in an iPhone app:

SDWebImageManager.sharedManager().downloadWithURL(url, options: 0, progress: nil) { (image:UIImage!, error:NSError!, cacheType:SDImageCacheType, finished:Bool) -> Void in
            // block code here
        }

Xcode will point out an error where it says options: 0 because 'Int' is not convertible to SDWebImageOptions. I've tried something like the following, but I get the same error:

let emptyOptions:SDWebImageOptions = 0

解决方案

As of Swift 2, the syntax for option sets was changed to use array literals. So if you want to pass no options, you pass an empty list:

SDWebImageManager.sharedManager().downloadWithURL(url, options: [], progress: nil) { (image:UIImage!, error:NSError!, cacheType:SDImageCacheType, finished:Bool) -> Void in
    // code here
}

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