UIPickerView cannot display JSON array data - ios

Question

This is my first time doing an iOS app, so I may not know some stuff that may seem easy. Please be patient with me =)
Basically, I need to fill up my UIPickerView with data from my JSON. I have successfully parsed my JSON data and pulled out what I need and placed them into an NSMutableArray. When I first tried to do the UIPickerView, I used hardcoded array, and everything was working fine. Now, when I try to replace the hardcoded array with my JSON array, I keep getting a null JSON array. The way it works, it seems that the UIPickerView tried to pull everything out before my JSON array is filled.
I have tried reloading the UIPickerView as suggested elsewhere on this site, and it also isn't working.
The following are parts of my code:
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
dispatch_async(randomiserBgQ, ^{
NSData* data = [NSData dataWithContentsOfURL:randomiserCatURL];
[self performSelectorOnMainThread:#selector(fetchedData:) withObject:data waitUntilDone:YES];
});
}
- (void)fetchedData:(NSData *)responseData{
NSError* error;
NSDictionary* json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
NSArray* randomiserCat = [json objectForKey:#"categories"];
self.randCatSel =[[NSMutableArray alloc] init];
NSLog(#"categories: %#", randomiserCat);
for (int i = 0; i < [randomiserCat count]; i++) {
NSDictionary *dict = [randomiserCat objectAtIndex:i];
NSString* parent = [dict objectForKey:#"name"];
[self.randCatSel addObject:parent];
NSArray* childrenArray = [dict objectForKey:#"children"];
for (int i = 0; i < [childrenArray count]; i++) {
NSDictionary* dict = [childrenArray objectAtIndex:i];
NSString* children = [dict objectForKey:#"name"];
[self.randCatSel addObject:children];
NSArray* grandchildrenArray = [dict objectForKey:#"grandchildren"];
for (int i = 0; i < [grandchildrenArray count]; i++) {
NSDictionary* dict = [grandchildrenArray objectAtIndex:i];
NSString* grandchildren = [dict objectForKey:#"name"];
[self.randCatSel addObject:grandchildren];
}
}
}
}
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent: (NSInteger)component
{
return [self.randCatSel count];
}
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
return [self.randCatSel objectAtIndex:row];
}
As you can see, the way I tried to parse my JSON data, I used such a long method as I have a few levels of arrays in the JSON data. If there is a faster method (like foreach in PHP), please point me in the right direction as well.
So far, my UIPickerView is getting a empty randCatSel array (I presume it is loading it before it is filled).

Answer 1

hi please try this,
- (void)fetchedData:(NSData *)responseData
{
NSError* error;
NSDictionary* json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error];
NSArray* randomiserCat = [json objectForKey:#"categories"];
self.randCatSel =[[NSMutableArray alloc] init];
NSLog(#"categories: %#", randomiserCat);
for (int i = 0; i < [randomiserCat count]; i++) {
NSDictionary *dict = [randomiserCat objectAtIndex:i];
NSString* parent = [dict objectForKey:#"name"];
[self.randCatSel addObject:parent];
NSArray* childrenArray = [dict objectForKey:#"children"];
for (int i = 0; i < [childrenArray count]; i++) {
NSDictionary* dict = [childrenArray objectAtIndex:i];
NSString* children = [dict objectForKey:#"name"];
[self.randCatSel addObject:children];
NSArray* grandchildrenArray = [dict objectForKey:#"grandchildren"];
for (int i = 0; i < [grandchildrenArray count]; i++) {
NSDictionary* dict = [grandchildrenArray objectAtIndex:i];
NSString* grandchildren = [dict objectForKey:#"name"];
[self.randCatSel addObject:grandchildren];
}
}
}
packerView=[[UIPickerView alloc] initWithFrame:CGRectMake(0, 280, 320, 200)];
packerView.delegate=self;
packerView.dataSource=self;
[self.view addSubview:packerView];
}
//add the picker view delegate and datasource in .h file. and set the frame as per your requirement.
hope this will help you.

Answer 2

As pointed out by the wonderful people here, all I had to do was to reload the UIPickerView in my fetchedData method. I previously put it in viewDidLoad =/
[pickerViewObj reloadAllComponents];
Where pickerViewObj is your own UIPickerView.