Swift:调用中的额外参数“错误" [英] Swift: Extra argument 'error' in call

问题描述

我目前正在使用 Swift 2.0 和 Xcode Beta 2 开发我的第一个 iOS 应用程序.它读取外部 JSON 并在包含数据的表视图中生成一个列表.但是，我遇到了一个似乎无法修复的奇怪小错误:

I'm currently developing my first iOS app using Swift 2.0 and Xcode Beta 2. It reads an external JSON and generates a list in a table view with the data. However, I'm getting a strange little error that I can't seem to fix:

Extra argument 'error' in call

这是我的代码片段:

let task = session.dataTaskWithURL(url!, completionHandler: {data, response, error -> Void in
            print("Task completed")

            if(error != nil){
                print(error!.localizedDescription)
            }

            var err: NSError?

            if let jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as? NSDictionary{

                if(err != nil){
                    print("JSON Error (err!.localizedDescription)")
                }

                if let results: NSArray = jsonResult["results"] as? NSArray{
                    dispatch_async(dispatch_get_main_queue(), {
                        self.tableData = results
                        self.appsTableView!.reloadData()
                    })
                }
            }
        })

在这一行抛出错误:

if let jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: &err) as? NSDictionary{

有人可以告诉我我在这里做错了什么吗?

Can someone please tell me what I'm doing wrong here?

推荐答案

在 Swift 2 中，NSJSONSerialization 的 signature 已更改为符合新的错误处理系统.

With Swift 2, the signature for NSJSONSerialization has changed, to conform to the new error handling system.

以下是如何使用它的示例:

Here's an example of how to use it:

do {
    if let jsonResult = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? NSDictionary {
        print(jsonResult)
    }
} catch let error as NSError {
    print(error.localizedDescription)
}

根据 Swift API 设计指南.

这是相同的例子:

do {
    if let jsonResult = try JSONSerialization.jsonObject(with: data, options: []) as? [String:AnyObject] {
        print(jsonResult)
    }
} catch let error as NSError {
    print(error.localizedDescription)
}

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