How do I deserialize a JSON string into an NSDictionary For iOS 5

Question

In my iOS 5 app  I have an NSString that contains a JSON string  I would like to deserialize that JSON string representation into a native NSDictionary object        password       1234       user       andreas       I tried the following approach   NSDictionary  json    NSJSONSerialization JSONObjectWithData      2     3                                     options NSJSONReadingMutableContainers                                   error  amp e       But it throws the a runtime error  What am I doing wrong   -   NSCFConstantString bytes   unrecognized selector sent to instance 0x1372c      Terminating app due to uncaught exception  NSInvalidArgumentException   reason   -   NSCFConstantString bytes   unrecognized selector sent to instance 0x1372c

User · Accepted Answer

It looks like you are passing an NSString parameter where you should be passing an NSData parameter   NSError  jsonError  NSData  objectData         2     3     dataUsingEncoding NSUTF8StringEncoding   NSDictionary  json    NSJSONSerialization JSONObjectWithData objectData                                       options NSJSONReadingMutableContainers                                          error  amp jsonError

User · Answer

I ve made a category from  Abizern answer    implementation NSString  Extensions  -  NSDictionary    json StringToDictionary       NSError  error      NSData  objectData    self dataUsingEncoding NSUTF8StringEncoding       NSDictionary  json    NSJSONSerialization JSONObjectWithData objectData options NSJSONReadingMutableContainers error  amp error       return   json   nil   json      end   Use it like this   NSString  jsonString        2     3      NSLog        jsonString json StringToDictionary

User · Answer

Using Abizern code for swift 2 2  let objectData   responseString  dataUsingEncoding NSUTF8StringEncoding  let json   try NSJSONSerialization JSONObjectWithData objectData   options  NSJSONReadingOptions MutableContainers

User · Answer

With Swift 3 and Swift 4  String has a method called data using allowLossyConversion    data using allowLossyConversion   has the following declaration   func data using encoding  String Encoding  allowLossyConversion  Bool   default  - gt  Data       Returns a Data containing a representation of the String encoded using a given encoding    With Swift 4  String s data using allowLossyConversion   can be used in conjunction with JSONDecoder s decode   from   in order to deserialize a JSON string into a dictionary   Furthermore  with Swift 3 and Swift 4  String s data using allowLossyConversion   can also be used in conjunction with JSONSerialization s json Object with  options    in order to deserialize a JSON string into a dictionary      1  Swift 4 solution  With Swift 4  JSONDecoder has a method called decode   from    decode   from   has the following declaration   func decode lt T gt    type  T Type  from data  Data  throws - gt  T where T   Decodable      Decodes a top-level value of the given type from the given JSON representation    The Playground code below shows how to use data using allowLossyConversion   and decode   from   in order to get a Dictionary from a JSON formatted String   let jsonString         password     1234     user     andreas        if let data   jsonString data using  String Encoding utf8        do           let decoder   JSONDecoder           let jsonDictionary   try decoder decode Dictionary lt String  String gt  self  from  data          print jsonDictionary     prints    user    andreas    password    1234         catch              Handle error         print error               2  Swift 3 and Swift 4 solution  With Swift 3 and Swift 4  JSONSerialization has a method called json Object with  options     json Object with  options    has the following declaration   class func jsonObject with data  Data  options opt  JSONSerialization ReadingOptions       throws - gt  Any      Returns a Foundation object from given JSON data    The Playground code below shows how to use data using allowLossyConversion   and json Object with  options    in order to get a Dictionary from a JSON formatted String   import Foundation  let jsonString       password       1234       user       andreas      if let data   jsonString data using  String Encoding utf8        do           let jsonDictionary   try JSONSerialization jsonObject with  data  options      as   String   String          print String describing  jsonDictionary      prints  Optional   user    andreas    password    1234          catch              Handle error         print error

User · Answer

NSData  data    strChangetoJSON dataUsingEncoding NSUTF8StringEncoding   NSDictionary  jsonResponse    NSJSONSerialization JSONObjectWithData data                                                              options kNilOptions                                                                error  amp error     For example you have a NSString with special characters in NSString strChangetoJSON  Then you can convert that string to JSON response using above code

[ios] How do I deserialize a JSON string into an NSDictionary? (For iOS 5+)

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