Display loading message until fully parsing json iOS - ios

Question

Ok here's the question, how do I simulate loading message until I fully downloaded the data from the server. I have this problem as I can't pass the data to the next view controller when the properties to hold the data from the downloaded json is still nil. So, How can I simulate a loading message until I fully parsed the Json.
Here's my code to fetch data
-(void)fetchFeed
{
NSString *requestString = #"some website";
NSURL *url = [NSURL URLWithString:requestString];
NSURLRequest *req = [NSURLRequest requestWithURL:url];
NSURLSessionDataTask *dataTask = [self.session dataTaskWithRequest:req completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSDictionary * jsonObject = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
self.locations = jsonObject[#"someKey"];
NSLog(#"%#", self.locations);
}
];
[dataTask resume];
}
- (void)viewDidLoad
{
[super viewDidLoad];
MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView:self.view];
[self.view addSubview:hud];
[hud show:YES];
[hud setLabelText:#"Loading..."];
dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
[self fetchFeed]; //Network activity
dispatch_async(dispatch_get_main_queue(), ^{
//do stuff after json download
[MBProgressHUD hideHUDForView:self.view animated:YES];
});
});

Answer 1

Please check out my answer here.. It pretty much does the same thing that you are looking for..
I have used MBProgressHUD to show the loading message.
Its as simple as
MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView:self.view];
[self.view addSubview:hud];
[hud show:YES];
[hud setLabelText:#"Loading..."];
dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
//Network activity
dispatch_async(dispatch_get_main_queue(), ^{
//do stuff after json download
[MBProgressHUD hideHUDForView:self.view animated:YES];
});
});
for a more detailed answer check the link.
*************EDIT*******************
As you are using NSURLSession it allows you to perform background download operations. As per the code you posted, we don't to start a new thread using dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{})
Please try this..
- (void)viewDidLoad
{
[super viewDidLoad];
[self fetchFeed]; //Network activity
}
-(void)fetchFeed
{
MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView:self.view];
[self.view addSubview:hud];
[hud show:YES];
[hud setLabelText:#"Loading..."];
NSString *requestString = #"some website";
NSURL *url = [NSURL URLWithString:requestString];
NSURLRequest *req = [NSURLRequest requestWithURL:url];
[[self.session dataTaskWithRequest:req completionHandler:^(NSData *data, NSURLResponse *response, NSError *error){
NSDictionary * jsonObject = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
self.locations = jsonObject[#"someKey"];
NSLog(#"%#", self.locations);
dispatch_async(dispatch_get_main_queue(), ^{
[MBProgressHUD hideHUDForView:self.view animated:YES];
});
}] resume];
}
This should work.