从这里抛出的Swift错误没有处理 [英] Swift Errors Thrown from here are not handled

问题描述

我已经在Xcode 6中使用了代码，但是由于我有Xcode 7，我无法弄清楚如何解决这个问题。 let jsonresult行有一个错误，表示从这里抛出的错误未被处理。代码如下：

  func connectionDidFinishLoading（connection：NSURLConnection！）{
 
 let jsonresult：NSDictionary =尝试NSJSONSerialization.JSONObjectWithData（self.bytes，options：NSJSONReadingOptions.MutableContainers）as！ NSDictionary 
 
 print（jsonresult）
 
 let number：Int = jsonresult [count] as！ Int 
 
 print（number）
 
 numberElements = number 
 
让结果：NSDictionary = jsonresult [results] as！ NSDictionary 
 
 let collection1：NSArray = results [collection1] as！ NSArray 
  

谢谢

解决方案

如果您查看swift 2中 JSONObjectWithData 方法的定义，则会抛出错误。

 类func JSONObjectWithData（data：NSData，options opt：NSJSONReadingOptions）throws  - > AnyObject 
  

在swift 2中，如果某些函数抛出错误，则必须用do-try-catch块

这是它的工作原理

  func connectionDidFinishLoading（connection： NSURLConnection！）{
 do {
 let jsonresult：NSDictionary = try NSJSONSerialization.JSONObjectWithData（self.bytes，options：NSJSONReadingOptions.MutableContainers）as！ NSDictionary 
 print（jsonresult）
 
 let number：Int = jsonresult [count] as！ Int 
 
 print（number）
 
 numberElements = number 
 
让结果：NSDictionary = jsonresult [results] as！ NSDictionary 
 
 let collection1：NSArray = results [collection1] as！ NSArray 
} catch {
 // handle error 
} 
} 
  

或者如果您不想要处理错误，可以使用 try！关键字强制执行。

  let jsonresult：NSDictionary = try！ NSJSONSerialization.JSONObjectWithData（self.bytes，options：NSJSONReadingOptions.MutableContainers）as！ NSDictionary 
 print（jsonresult）
  

与其他关键字结束！这是一个危险的操作。如果您的程序出现错误，您的程序将崩溃。

I have had my code working in Xcode 6 but since I got Xcode 7 I cannot figure out how to fix this. The let jsonresult line has an error that says Error thrown from here are not handled. Code is below:

func connectionDidFinishLoading(connection: NSURLConnection!) {

    let jsonresult:NSDictionary = try NSJSONSerialization.JSONObjectWithData(self.bytes, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary

    print(jsonresult)

    let number:Int = jsonresult["count"] as! Int

    print(number)

    numberElements = number

    let results: NSDictionary = jsonresult["results"] as! NSDictionary

    let collection1: NSArray = results["collection1"] as! NSArray

Thanks

解决方案

If you look at the definition of JSONObjectWithData method in swift 2 it throws error.

class func JSONObjectWithData(data: NSData, options opt: NSJSONReadingOptions) throws -> AnyObject

In swift 2 if some function throws an error you have to handle it with do-try-catch block

Here is how it works

func connectionDidFinishLoading(connection: NSURLConnection!) {
    do {
        let jsonresult:NSDictionary = try NSJSONSerialization.JSONObjectWithData(self.bytes, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
        print(jsonresult)

        let number:Int = jsonresult["count"] as! Int

        print(number)

        numberElements = number

        let results: NSDictionary = jsonresult["results"] as! NSDictionary

        let collection1: NSArray = results["collection1"] as! NSArray
    } catch {
        // handle error
    }
}

Or if you don't want handle error you can force it with try! keyword.

let jsonresult:NSDictionary = try! NSJSONSerialization.JSONObjectWithData(self.bytes, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
        print(jsonresult)

As with other keywords that ends ! this is a risky operation. If there is an error your program will crash.

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