Use NSArray object outside from json object - ios

Question

I'm new to Objective-C, just wondering how to use NSArray object outside from JSON.
For example:
NSURL *url = [NSURL URLWithString:#"http://acumen-locdef.elasticbeanstalk.com/service/countries"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSMutableArray *myFinalListArray = [[NSMutableArray alloc] init];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data, NSError *connectionError)
{
if (data.length > 0 && connectionError == nil)
{
NSMutableArray *greeting = [NSJSONSerialization JSONObjectWithData:data
options:0
error:NULL];
for (NSDictionary *countryList in greeting) {
[myFinalListArray addObject:countryList[#"name"]];
}
}
NSLog(#"%#",myFinalListArray); //(This one showing all results..)
}];
NSLog(#"%#",myFinalListArray); //(This one giving empty result)
I have defined myFinalListArray and added objects in for loop.
If you use NSLog inside the loop or outside the loop it will show you results. But if I use this after }]; (after the code is ending.),
it's giving me empty array.

Answer 1

If you are accessing myFinalListArray in tableview then you can reload tableview inside the block after fetching data.
Or if you are accessing this array in some other task then you have to make notification call (have to add observer) and then post notification that will call some other method and access your array there and do your further stuff.

Answer 2

The block of code associated with sendAsynchronousRequest isn't executed until the network fetch has completed; this takes some time. While the network fetch is happening your code continues to execute, starting with the line immediately after sendAsynchronousRequest which is NSLog(#"%#",myFinalListArray); - but because the network operation hasn't completed you get an empty array.
In the block you need to include the code that you need to process the array, update your user interface or whatever (If you update UI make sure you dispatch the operation on the main thread)

Answer 3

This will work. You can try with this.
- (void)viewDidLoad {
[super viewDidLoad];
NSMutableArray *myFinalListArray = [[NSMutableArray alloc] init];
//Pass here the reference the a array. It will return you the array of you county when downloaded complete.
[self getURLResponse:&myFinalListArray];
NSLog(#"countryArray:%#",myFinalListArray);
}
-(void)getURLResponse:(NSMutableArray**)countryArray{
NSURL *url = [NSURL URLWithString:#"http://acumen-locdef.elasticbeanstalk.com/service/countries"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSMutableArray *myFinalListArray = [[NSMutableArray alloc] init];
NSURLResponse *response;
NSError *error = nil;
NSData *data = [NSURLConnection sendSynchronousRequest:
request returningResponse:&response error:&error];
NSMutableArray *greeting = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
for (NSDictionary *countryList in greeting) {
[myFinalListArray addObject:countryList[#"name"]];
}
*countryArray = [[NSMutableArray alloc]initWithArray:myFinalListArray copyItems:YES];
}

Answer 4

-(void)sendRequest
{
NSURL *url = [NSURL URLWithString:#"http://acumen-locdef.elasticbeanstalk.com/service/countries"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSMutableArray *myFinalListArray = [[NSMutableArray alloc] init];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,
NSData *data, NSError *connectionError) {
if (data.length > 0 && connectionError == nil)
{
NSMutableArray *greeting = [NSJSONSerialization JSONObjectWithData:data
options:0
error:NULL];
if( !myFinalListArray )
{
myFinalListArray=[[NSMutableArray alloc]init];
}
for (NSDictionary *countryList in greeting) {
[myFinalListArray addObject:countryList[#"name"]];
}
}
[self printArray];
}];
}
//create method that will execute after response
-(void) printArray
{
NSLog(#"%#",myFinalListArray); //(This one showing all results..)
}

Answer 5

Use
__block NSMutableArray *myFinalListArray = [[NSMutableArray alloc] init];
This should work.
Happy Coding.

Answer 6

sendAsynchronousRequest runs asynchronously, meaning that the code below is already performed while the request is still running, so the NSLog is logging the empty array.
Only when the request finishes, the array is filled up but your outer NSLog was already performed.