如何将JSON字符串转换为字典? [英] How to convert a JSON string to a dictionary?

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问题描述


我无法转换,我想在我的swift项目中使一个函数转换为字典json格式,但是我有一个错误:表达式的类型(@lvalue NSData,选项:IntegerLitralConvertible ...


这是我的代码:

  func convertStringToDictionary(text:String) - > Dictionary< String,String> {

var data:NSData = text.dataUsingEncoding(NSUTF8StringEncoding )
var json:Dictionary = NSJSONSerialization.JSONObjectWithData(data,options:0,error:nil)
return json
}

我在Objective-C中进行此功能:

   - ( NSDictionary *)convertStringToDictionary:(NSString *)string {
NSError * error;
//给出错误,因为它只需要dic,数组等,而不是自定义对象
NSData * data = [ string dataUsingEncoding:NSUTF8StringEncoding];
id json = [NSJSONSerialization JSONObjectWi thData:数据选项:0错误:& error];
return json;
}


解决方案

/ strong>

  func convertToDictionary(text:String) - > [String:Any]? {
if let data = text.data(using:.utf8){
do {
return try JSONSerialization.jsonObject(with:data,options:[])as? [String:Any]
} catch {
print(error.localizedDescription)
}
}
return nil
}

let str ={\name \:\James \}

let dict = convertToDictionary(text:str)

Swift 2

  func convertStringToDictionary(text:String) - > [字符串:AnyObject]? {
if let data = text.dataUsingEncoding(NSUTF8StringEncoding){
do {
return try NSJSONSerialization.JSONObjectWithData(data,options:[])as? [String:AnyObject]
} catch let error as NSError {
print(error)
}
}
return nil
}

let str ={\name\:\James \}

let result = convertStringToDictionary(str)

原始Swift 1答案

 code> func convertStringToDictionary(text:String) - > [字符串:字符串]? {
if let data = text.dataUsingEncoding(NSUTF8StringEncoding){
var error:NSError?
let json = NSJSONSerialization.JSONObjectWithData(data,options:NSJSONReadingOptions.allZeros,error:& error)as? [String:String]
如果错误!= nil {
println(错误)
}
返回json
}
返回nil
}

let str ={\name\:\James \}

let result = convertStringToDictionary(str)// [name :James]

如果let name = result?[name] {//```在这里是因为我们的`convertStringToDictionary`函数返回一个可选的
println )//James
}

在您的版本中,您没有通过适当的参数为 NSJSONSerialization ,忘记投射结果。另外,最好检查可能的错误。最后一个注意事项:只有当你的值是一个字符串时,这才有效。如果可以是另一种类型,最好是这样声明字典转换:

  let json = NSJSONSerialization.JSONObjectWithData数据,选项:NSJSONReadingOptions.allZeros,错误:& error)为? [String:AnyObject] 

当然,您还需要更改函数的返回类型:

  func convertStringToDictionary(text:String) - > [字符串:AnyObject]? {...} 


I want to make one function in my swift project that converts String to Dictionary json format but I got one error:

Cannot convert expression's type (@lvalue NSData,options:IntegerLitralConvertible ...

This is my code:

func convertStringToDictionary (text:String) -> Dictionary<String,String> {

    var data :NSData = text.dataUsingEncoding(NSUTF8StringEncoding)!
    var json :Dictionary = NSJSONSerialization.JSONObjectWithData(data, options:0, error: nil)
    return json
} 

I make this function in Objective-C :

- (NSDictionary*)convertStringToDictionary:(NSString*)string {
  NSError* error;
  //giving error as it takes dic, array,etc only. not custom object.
  NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
  id json = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
  return json;
}

解决方案

Swift 3

func convertToDictionary(text: String) -> [String: Any]? {
    if let data = text.data(using: .utf8) {
        do {
            return try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any]
        } catch {
            print(error.localizedDescription)
        }
    }
    return nil
}

let str = "{\"name\":\"James\"}"

let dict = convertToDictionary(text: str)

Swift 2

func convertStringToDictionary(text: String) -> [String:AnyObject]? {
    if let data = text.dataUsingEncoding(NSUTF8StringEncoding) {
        do {
            return try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String:AnyObject]
        } catch let error as NSError {
            print(error)
        }
    }
    return nil
}

let str = "{\"name\":\"James\"}"

let result = convertStringToDictionary(str)

Original Swift 1 answer:

func convertStringToDictionary(text: String) -> [String:String]? {
    if let data = text.dataUsingEncoding(NSUTF8StringEncoding) {
        var error: NSError?
        let json = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.allZeros, error: &error) as? [String:String]
        if error != nil {
            println(error)
        }
        return json
    }
    return nil
}

let str = "{\"name\":\"James\"}"

let result = convertStringToDictionary(str) // ["name": "James"]

if let name = result?["name"] { // The `?` is here because our `convertStringToDictionary` function returns an Optional
    println(name) // "James"
}

In your version, you didn't pass the proper parameters to NSJSONSerialization and forgot to cast the result. Also, it's better to check for the possible error. Last note: this works only if your value is a String. If it could be another type, it would be better to declare the dictionary conversion like this:

let json = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.allZeros, error: &error) as? [String:AnyObject]

and of course you would also need to change the return type of the function:

func convertStringToDictionary(text: String) -> [String:AnyObject]? { ... }

这篇关于如何将JSON字符串转换为字典?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IT屋!

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