HTTPS data returned not saving - objective-c

Question

I have an object class set up called WebCalls. In this class, I make a web call and return some JSON from an HTTPS server. Now the methods work perfectly, I have tested and the data returns fine. However my problem is, I can't access the data returned outside the class.
The code to retrieve the data is below
Interface
#interface WebCall : NSObject{
NSString *phoneNumber;
NSString *jsonData;
}
#property (nonatomic, retain) NSMutableData *responseData;
#property (nonatomic, retain) NSString *jsonData;
-(void) getData: (NSString *) link;
#end
Implementation
#implementation WebCall
#synthesize jsonData;
#synthesize responseData;
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
[responseData setLength:0];
}
- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace {
return [protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];
}
- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
[challenge.sender useCredential:[NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust] forAuthenticationChallenge:challenge];
[challenge.sender continueWithoutCredentialForAuthenticationChallenge:challenge];
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[responseData appendData:data];
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
self.responseData = nil;
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSString *s = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
jsonData = s;
}
-(void) getData: (NSString *) link{
jsonData = [[NSString alloc] init];
self.responseData = [NSMutableData data];
NSURL * url = [NSURL URLWithString:link];
NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:url];
[request addValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[request setHTTPMethod:#"GET"];
[[NSURLConnection alloc]initWithRequest:request delegate:self startImmediately:YES];
}
#end
In interface class I have a string called jsonData. I get and set it using property and synthesise. So after I make web call, I assign the data to jsonData, and I should be able to import web call class, use the getInfo method, have the jsonData returned and then access it using
WebCall *wc = [[WebCall alloc] init];
[wc getData:url];
NSLog(#"%#", [c jsonData]);
However this just prints out null. And yet if I print out the String in the Webcall class after I recieve the data, it prints out fine. Could anyone tell me what I am doing wrong?
Thanks in advance
Edit: Updated with complete implementation
Also I can't access the string outside the method. I copied the code to another class, and tried assigning the JSON String, then calling it again in the body, and it comes out null again. Seems I can only print it out in that connection method. Then it seems to clear the String
Edit: What I tried
[wc setWebCallDidFinish:^(NSString * json, NSString *test){
NSLog(#"%#", json);
}];
[wc getData:#"12345"];

Answer 1

Adam the reason jsonData is an empty string is because [[NSURLConnection alloc]initWithRequest:request delegate:self startImmediately:YES]; runs asynchronously which means on a new thread and it doesn't block. this means that when you call [wc getData:url]; and then immediately call NSLog(#"%#", [wc jsonData]); the http request hasn't completed yet and the - (void)connectionDidFinishLoading:(NSURLConnection *)connection delegate function hasn't been called yet in your WebCall.
For a detailed explanation read this iOs Concurrency Programming Guide. Essentially you need to add a notifier to your WebCall so that it can notify the object which spawns it that the request has finished loading. I would use a block like so.
#interface WebCall : NSObject{
NSString *phoneNumber;
NSString *jsonData;
void(^webCallDidFinish)(NSString *jsonData, id otherRandomVar);
}
#property (nonatomic, retain) NSMutableData *responseData;
#property (nonatomic, retain) NSString *jsonData;
-(void) getData: (NSString *) link;
-(void)setWebCallDidFinish:(void (^)(NSString *, id))wcdf;
#end
Implementation
#implementation WebCall
#synthesize jsonData;
#synthesize responseData;
-(void)setWebCallDidFinish:(void (^)(NSString *,id))wcdf{
webCallDidFinish = [wcdf copy];
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
NSString *s = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
jsonData = s;
webCallDidFinish(jsonData, #"any other object");
}
//all of your other code here
Then in the calling code the following
WebCall *wc = [[WebCall alloc] init];
[wc setWebCallDidFinish:^(NSString * json, id randomSecondVar) {
NSLog(#"%#",json);
}];
[wc getData:url];
What will happen is the block of code you provide to setWebCallDidFinish will be called after jsonData is loaded. You could also use the Delegate pattern to accomplish this. Note that while this asynchronous request is loading you should provide some sort of indicator to your user.