Data from API call not filling inside of method - ios

Question

I decided to go with an embedded API call within a view controller, and I'm having trouble with the data reaching out before the API returns with the information.
How do I wait for the data to be returned before the view controller displays all the values as nulls?
Thanks for any help.
#import "BDChangeApproveController.h"
#import "BDItemChangeDetailAPI.h"
#interface BDChangeApproveController () <NSURLSessionDelegate>
#property (nonatomic, strong) NSURLSession *session;
#property (nonatomic, copy) NSArray *APIItem;
#end
#implementation BDChangeApproveController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)fetchFeedAPIChangeDetail
{
NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
_session = [NSURLSession sessionWithConfiguration:config
delegate:nil
delegateQueue:nil];
NSString *requestString = #"http://URL.com";
NSURL *url = [NSURL URLWithString:requestString];
NSURLRequest *req = [NSURLRequest requestWithURL:url];
NSURLSessionDataTask *dataTask =
[self.session dataTaskWithRequest:req
completionHandler:
^(NSData *data, NSURLResponse *response, NSError *error){
NSDictionary *jsonObject1 = [NSJSONSerialization JSONObjectWithData:data
options:0
error:nil];
//NSLog(#"%#", jsonObject1);
self.APIItem = jsonObject1[#"CoDetail"];
NSLog(#"%#", self.APIItem);
}];
[dataTask resume];
}
//API authentication
- (void) URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge
completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential *))completionHandler
{
NSURLCredential *cred =
[NSURLCredential credentialWithUser:#"demouser"
password:#"secret"
persistence:NSURLCredentialPersistenceForSession];
completionHandler(NSURLSessionAuthChallengeUseCredential, cred);
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self fetchFeedAPIChangeDetail];
self.title = #"Action";
self.coNumberLabel.text = self.itemAPI.changeOrder;
//self.recipeImageView.image = [UIImage imageNamed:self.recipe.image];
NSLog(#"testtttt");
NSMutableString *coDetailsText = [NSMutableString string];
coDetailsText =
[[NSMutableString alloc] initWithFormat:#"Review Change Order details bellow\n====================\n%# \n================== \nPlanned Start %#\n==================\nSubcategory: %#\n==================\nService: %#\n==================\nAssociated CIs: %#\n==================\nEnvironment CI: %#\n==================\nApproval Group: %#\n==================\nInitiator : %#\n==================\nCoordinator : %#\n==================\nRisk Level : %#\n==================\nPerforming Group : %#\n==================\nImplementation Plan : %#\n==================\nStatus : %#\n==================\nRecovery Plan : %#\n==================\n",
/*
self.item.title,
self.item.changeOrder,
self.item.subcategory,
self.item.assignmentGroup,
self.item.changeOrder,
self.item.subcategory,
self.item.assignmentGroup,
self.item.approverEid,
self.item.approverEid,
self.item.subcategory,
self.item.assignmentGroup,
self.item.title,
self.item.title,
self.item.title
*/
self.itemAPI.title,
self.itemAPI.plannedStart,
self.itemAPI.subcategory,
self.itemAPI.service,
self.itemAPI.associatedCi,
self.itemAPI.environment,
self.itemAPI.assignmentGroup,
self.itemAPI.initiator,
self.itemAPI.coordinator,
self.itemAPI.riskLevel,
self.itemAPI.performingGroup,
self.itemAPI.implementationPlan,
self.itemAPI.status,
self.itemAPI.recoveryScope
// self.item.valueInDollars,
// self.item.dateCreated,
// self.item.subcategory,
// self.item.service,
// self.item.associatedCIs,
// self.item.environment,
// self.item.approvalGroup,
// self.item.initiator,
// self.item.coordinator,
// self.item.riskLevel,
// self.item.performingGroup,
// self.item.implementationPlan,
// self.item.validationPlan,
//self.item.recoveryScope
];
self.coDetailsTextView.text = coDetailsText;
NSLog(#"overrrr");
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
// Adding File
#import <Foundation/Foundation.h>
#import "BDItemChangeDetailAPI.h"
#interface BDChangeApproveController : UIViewController
#property (weak, nonatomic) IBOutlet UILabel *coNumberLabel;
#property (weak, nonatomic) IBOutlet UITextView *coDetailsTextView;
#property (nonatomic, strong) BDItemChangeDetailAPI *itemAPI;
#end

Answer 1

Looks like you're doing something asynchronously and expecting it to act synchronously.
Look at the below piece of code you're using in viewDidLoad:
[self fetchFeedAPIChangeDetail]; // this takes some time to complete
self.title = #"Action"; // this happens immediately after the above starts, not ends
self.coNumberLabel.text = self.itemAPI.changeOrder; // so does this, so at this point itemAPI is probably nil
fetchFeedAPICheckDetail is an asynchronous process, so it might take a few seconds to complete, whereas setting the title and coNumberLabel happens immediately after, so you don't yet have the itemAPI information from the URL Session. Your code doesn't wait for fetchFeedAPIChangeDetail to be done with the request before continuing onto the next line.

Answer 2

Declare a function
-(void)refreshTextView
{
// set your text view text with the api result here
self.coNumberLabel.text = self.itemAPI.changeOrder;
}
Call this method in at the end of your request block after NSLog(#"%#", self.APIItem);
Like this
[self performSelectorOnMainThread:#selector(refreshTextView) withObject:nil waitUntilDone:NO];
When you will call this method in the block it will be called and will update the textview text with the api results. The block is asynchronous and so when you update your textview later it doesn't gets updated because the block has not yet completed its function and the array is still nil but calling this method in the block would assure that the result gets assigned and updated in the textview.
UPDATE
and you do have a typo here
#property (nonatomic, copy) NSArray *APIItem;
you are naming it with the class name thats a conflict.
Name it something else like #property (nonatomic, copy) NSArray *apiItem; Actually u have a class name APIItem declared because of which a conflict occurs and that is the very reason it is marked blue in xcode. look all class names are marked blue in your code. Like NSArray , NSURLSession etc –