delegate method cannot callback - ios

Question

delegate method cannot callback
This is my .h file
#protocol ServiceAPIDelegate <NSObject>
#optional
- (void) onRequestLoginFinish:(NSDictionary*) dict;
#end
#interface ServiceAPI : NSObject
+ (id)shareAPI;
#property (nonatomic, weak) id <ServiceAPIDelegate> delegate_service;
;
#end
and this is .m file, i use ASIFORMData request and it is callback to requestFinished after get a response from server. but ater that, i want to send data to myviewcontroler use [self.delegate_service onRequestLoginFinish:result]; after this line. my program run normaly not bugs, not callback to function. I cannot see where errors are.
- (void) requestLoginWithUserName:(NSString*) username andPassWord:(NSString*) password {
NSString* urlString = [PublicInstance API_LOGIN];
NSArray *keys = PARAMS_ARRAY;
NSArray *objects = [NSArray arrayWithObjects:username, password, [#((int)En) stringValue], APPID, [PublicInstance getDevideID], DEVIDEOS, nil];
NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithObjects:objects forKeys:keys];
NSString* signData = [PublicInstance signData:dict];
[dict setObject:signData forKey:signKey];
ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:[NSURL URLWithString:urlString]];
[request addRequestHeader:#"Content-Type" value:#"application/json"];
[request setValidatesSecureCertificate:NO];
[request setRequestMethod:#"POST"];
NSData *jsonDataToPost = [NSJSONSerialization dataWithJSONObject:dict options:0 error:nil];
[request appendPostData:jsonDataToPost];
[request startAsynchronous];
[request setDelegate:self];
}
- (void)requestFinished:(ASIHTTPRequest *)request
{
NSError* error = [request error];
if(!error) {
NSString* responseString = [request responseString];
NSDictionary *result = [NSJSONSerialization JSONObjectWithData;
[self.delegate_service onRequestLoginFinish:result];
}else{
NSLog(#"%#", [error description]);
}
}
ServiceAPI *ShareServiceAPI;
- (id) init {
if ([self init]) {
ShareServiceAPI = [ServiceAPI shareAPI];
ShareServiceAPI.delegate_service =self;
}
}
- (void) requestLoginWithUserInfor:(UserInfor*) _userinfor {
[ShareServiceAPI requestLoginWithUserName:_userinfor.username andPassWord:_userinfor.password];
}
#####################
and this is delegate method - but never callback (O^-oO)
- (void) onRequestLoginFinish:(NSDictionary *)dict {
if ([[dict objectForKey:Key_Status] intValue] == 1) {
NSLog(#"login successful");
}
else {
NSLog(#"login fail....");
}
}
Could anyone please help me?. Thank you for your time

Answer 1

You should always check if the delegate is nil or not and also check if the delegate responds to the selector as :
if(self.delegate_service){
if([self.delegate_service repondsToSelector:#selector(onRequestLoginFinish:)]){
[self.delegate_service onRequestLoginFinish:result];
}
}
Through the way you can make your program safe and found the reason that the method is not called.