Activity Indicator on a button click in IOS - ios

Question

I have a button of submitting form data to the service. When user click it it submit data and give alert of success. I want to add activity indicator in it , when user click button of submit the time it takes to submit the data the activity indicator should move and than hide when it data is submitted.I'm confused where should i use it in the code , I'm confused at that whether it shall be call after response or anywhere else. My code is,
NSString *post = [NSString stringWithFormat:#"propertyfor=%#&propertytype=%#&landarea=%#&country=%#&city=%#&price=%#&description=%#&location=%#&name=%#&email=%#&phone=%#",_propertyfor,_propertytype,_landarea,_country,_city,_price,_propdes,_propdescrip,self.name.text,self.email.text,phone];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:#"%lu", (unsigned long)[postData length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:[NSURL URLWithString:#"My URL"]];
[request setHTTPMethod:#"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setHTTPBody:postData];
NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
[[session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSString *requestReply = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(#"requestReply: %#", requestReply);
}] resume];

Answer 1

**//Start Activity Indicator here.**
NSString *post = [NSString stringWithFormat:#"propertyfor=%#&propertytype=%#&landarea=%#&country=%#&city=%#&price=%#&description=%#&location=%#&name=%#&email=%#&phone=%#",_propertyfor,_propertytype,_landarea,_country,_city,_price,_propdes,_propdescrip,self.name.text,self.email.text,phone];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:#"%lu", (unsigned long)[postData length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:[NSURL URLWithString:#"My URL"]];
[request setHTTPMethod:#"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setHTTPBody:postData];
NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
[[session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
**//Stop Activity Indicator here.**
NSString *requestReply = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(#"requestReply: %#", requestReply);
}] resume];

Answer 2

You need to start animating before session created and stop animating one you get reply. In your code :
.
.
.
.
[activity startAnimating];
NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
[[session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSString *requestReply = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
dispatch_async(dispatch_get_main_queue(), ^{
[activity stopAnimating];
});
NSLog(#"requestReply: %#", requestReply);
}] resume];

Answer 3

Replace followind code with original:
CGSize s1 = UIApplication.sharedApplication.windows[0].frame.size;
CGRect r1 = CGRectMake(s1.width/2-20, s1.height/2-20, 40, 40);
UIActivityIndicatorView *act = [[UIActivityIndicatorView alloc]initWithFrame:r1];
[self.view addSubview:act];
[act startAnimating];
NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
[[session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSString *requestReply = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(#"requestReply: %#", requestReply);
[act stopAnimating];
[act removeFromSuperview];
}] resume];