如何在Xcode中使用JSON发送数据

Question

I am writing a dictionary app for iOS.

I need to translate from one language to another.

I have 2 textViews. In the first one (textView1) I have to type a word I want to translate, in the 2nd one (textView) the translation must appear when I press button "Translate". So I need to send

{"SourceText":"%@","CheckCode":"something","TranslateDirection":"0","SubjectBase":"8"},[[self textView1] text] .

Assume my URL API is : http://fakesite.com/api/fake . What am I doing wrong?

-(IBAction)translate
{
    NSString *post = [NSString stringWithFormat:@"{\"SourceText\":\"%@\",\"CheckCode\":\something\",\"TranslateDirection\":\"0\",\"SubjectBase\":\"8\"}",[[self textView1] text]];
    NSData *postData = [post dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];

    NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
    [request setURL:[NSURL URLWithString:@"http://fakesite.com/api/fake"]];
    [request setHTTPMethod:@"POST"];
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/x-www-form-urlencoded;charset=UTF-8" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:postData];
    NSURLResponse *response;
    NSData *POSTReply = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];
    NSString *theReply = [[NSString alloc] initWithBytes:[POSTReply bytes] length:[POSTReply length] encoding: NSUTF8StringEncoding ];
    _textView.text=theReply;
}

And when I am pressing " Translate Button " the following message in the 2nd textView occurs: {"Message":"An error has occurred."} Look I have done this in java for Android, but as I am new to Xcode I am confused how to do it. Here are my java files as EXAMPLE. Mainactivity.java

public class MainActivity extends Activity implements OnClickListener {

public String URL = "http://fakesite.com/api/fake";
EditText text_input;
EditText output;
Button but_tr;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.user_interface);
    if (android.os.Build.VERSION.SDK_INT > 9) {
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);
    }


    output = (EditText) findViewById(R.id.text_output);
    but_tr = (Button) findViewById(R.id.button_translate);




    // add click listener to Button "POST"
    but_tr.setOnClickListener(this);

}

 @Override
    public void onClick(View view) {                                    
     String txt = text_input.getText().toString();
     List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(4);  
     nameValuePairs.add(new BasicNameValuePair("SourceText", txt));
     nameValuePairs.add(new BasicNameValuePair("CheckCode", "1q2w3e"));
     nameValuePairs.add(new BasicNameValuePair("TranslateDirection", "0"));
     nameValuePairs.add(new BasicNameValuePair("SubjectsBase", "8"));       
     API_Post post = new API_Post(URL, nameValuePairs);
     String Response = post.postData().toString().replace("\\r\\n", "");
     output.setText(Response.substring(51, Response.length() -2).replace("\\n", System.getProperty("line.separator")));         
    }   

}

API_Post.java

public class API_Post {
String url;
List<NameValuePair> nameValuePairs;
public API_Post(String str, List<NameValuePair> params) {
 this.url = str;
  this.nameValuePairs = params;
}
public String postData() {
 HttpClient httpclient = new DefaultHttpClient();  
 HttpPost httppost = new HttpPost(this.url);
StringBuilder builder = new StringBuilder();
try {
httppost.setEntity(new UrlEncodedFormEntity(this.nameValuePairs, HTTP.UTF_8 ));
HttpResponse response = httpclient.execute(httppost);
StatusLine statusLine = response.getStatusLine();
      int statusCode = statusLine.getStatusCode();
 Log.d("RestClient", "Status Code : " + statusCode);
 HttpEntity entity = response.getEntity();
InputStream content = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(
content));
 String line;
while ((line = reader.readLine()) != null) {
builder.append(line);
{
      builder.append(line);
  }
} catch (ClientProtocolException e) {
} catch (IOException e) {
}
return builder.toString();
}
}

So I need similar code for Xcode. Thanks

Answer 1

Use ASIHTTP third-party library it will save your time.

NSString *post = [NSString stringWithFormat:@"{\"SourceText\":\"%@\",\"CheckCode\":\something\",\"TranslateDirection\":\"0\",\"SubjectBase\":\"8\"}",[[self textView1] text]];
NSData *postData = [post dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES]; 

ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:[NSURL URLWithString:@"http://fakesite.com/api/fake"]];
[request setRequestMethod:@"POST"];
[request setResponseEncoding:NSISOLatin1StringEncoding];
[request setPostFormat:ASIMultipartFormDataPostFormat];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setHTTPBody:postData];
[request setValue:@"application/x-www-form-urlencoded;charset=UTF-8" forHTTPHeaderField:@"Content-Type"];

[request setCompletionBlock:^{

    NSDictionary *responseDict = [NSDictionary dictionaryWithXMLData:[request responseData]];

    DLog(@"Response : %@",responseDict);


}];
[request setFailedBlock:^{

}];

[request startAsynchronous];

Answer 2

You can try with below Obj C code:

    NSData *postData = [poststring dataUsingEncoding:NSUTF8StringEncoding];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:feedURLString]  cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:120];

    [request setHTTPMethod:@"POST"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:postData];
    conn=[[NSURLConnection alloc] initWithRequest:request delegate:self];

Before that to check if the Api is correct or wrong you can use the Google Postman.

Answer 3

I would recommend you, to check this tutorial . This way it is reausable also in other projects and you have a single class for each object in your request which might be easier to handle. So you just have to change the requests objects every time you use it again.

Answer 4

I believe the problem is with the json message , you are sending. Its Just a string in json format, but not the actual json object.

follow the same way, you used in Android code. Use NSDictionary instead of namevaluepairs in android and then get the json representation as follows.

NSString *jsonRequest = [jsonDict JSONRepresentation];

After this do URL encode and set as http body.