arrays - Swift:检查 jsonObjectWithData 是否为 json

Question

我有一个通过 http 与服务器通信的 swift 应用程序，

我从这个服务器得到的答案可能是json，也可能不是。我需要检查它们是什么，以便将答案打印为 Dictionary 或 Array，以避免 fatal error: unexpectedly found nil while unwrapping an NSJSONSerialization.JSONObjectWithData(dataVal, options: NSJSONReadingOptions.MutableContainers, error: nil) 中的可选值 as! NSDictionary

这是我的jsonObjectWithData:

var dataVal: NSData =  NSURLConnection.sendSynchronousRequest(request, returningResponse: &response, error:nil)!
elimResponse = response?.description        
elim = NSJSONSerialization.JSONObjectWithData(dataVal, options: NSJSONReadingOptions.MutableContainers, error: nil) as! NSDictionary

我试图得到的是这样的:

if dataVal is Json{
    elim = NSJSONSerialization.JSONObjectWithData(dataVal, options: NSJSONReadingOptions.MutableContainers, error: nil) as! NSDictionary
    println(elimJson)
    }else{
    elim = NSJSONSerialization.JSONObjectWithData(dataVal, options: NSJSONReadingOptions.MutableContainers, error: nil) as! NSArray
    println(elim)
    }

感谢您的帮助。问候。

Answer 1

您可以像这样在 if let 中尝试强制转换:

if let elim = NSJSONSerialization.JSONObjectWithData(dataVal, options: nil, error: nil) as? NSDictionary {
    println("elim is a dictionary")
    println(elim)
} else if let elim = NSJSONSerialization.JSONObjectWithData(dataVal, options: nil, error: nil) as? NSArray {
    println("elim is an array")
    println(elim)
} else {
    println("dataVal is not valid JSON data")
}

---

Swift 2.0 更新

do {
    if let elim = try NSJSONSerialization.JSONObjectWithData(dataVal, options: []) as? NSDictionary {
        print("elim is a dictionary")
        print(elim)
    } else if let elim = try NSJSONSerialization.JSONObjectWithData(dataVal, options: []) as? NSArray {
        print("elim is an array")
        print(elim)
    } else {
        print("dataVal is not valid JSON data")
    }
} catch let error as NSError {
    print(error)
}