Images from my UIPickerView disappear - iphone

Question

I am building an App where the user can spin a UIPickerView like a slot machine. The problem I am facing at the moment that at runtime the images in my pickerView start disappearing at random. Then spin again and some of them are back.
Here is the code I use to make the array of images (in my project there are 17 images in every array but to save a bit of space I narrowed it down):
- (void)viewDidLoad{
[super viewDidLoad];
[drinkPickerView_ selectRow:1000 inComponent:0 animated:NO];
[drinkPickerView_ selectRow:1000 inComponent:1 animated:NO];
[drinkPickerView_ selectRow:1000 inComponent:2 animated:NO];
if (managedObjectContext_ == nil)
{
managedObjectContext_ = [(AppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
}
drinkPickerView_.delegate = self;
drinkPickerView_.dataSource = self;
UIImage *fris1 = [UIImage imageNamed:#"fris01.PNG"];
UIImage *fris2 = [UIImage imageNamed:#"fris02.PNG"];
UIImage *fris3 = [UIImage imageNamed:#"fris03.PNG"];
UIImage *fris4 = [UIImage imageNamed:#"fris04.PNG"];
UIImage *fris5 = [UIImage imageNamed:#"fris05.PNG"];
UIImageView *frisView1 = [[UIImageView alloc]initWithImage:fris1];
UIImageView *frisView2 = [[UIImageView alloc]initWithImage:fris2];
UIImageView *frisView3 = [[UIImageView alloc]initWithImage:fris3];
UIImageView *frisView4 = [[UIImageView alloc]initWithImage:fris4];
UIImageView *frisView5 = [[UIImageView alloc]initWithImage:fris5];
UIImage *alcoholisch1 = [UIImage imageNamed:#"alcohol01.PNG"];
UIImage *alcoholisch2 = [UIImage imageNamed:#"alcohol02.PNG"];
UIImage *alcoholisch3 = [UIImage imageNamed:#"alcohol03.PNG"];
UIImage *alcoholisch4 = [UIImage imageNamed:#"alcohol04.PNG"];
UIImage *alcoholisch5 = [UIImage imageNamed:#"alcohol05.PNG"];
UIImageView *alcoholischView1 = [[UIImageView alloc]initWithImage:alcoholisch1];
UIImageView *alcoholischView2 = [[UIImageView alloc]initWithImage:alcoholisch2];
UIImageView *alcoholischView3 = [[UIImageView alloc]initWithImage:alcoholisch3];
UIImageView *alcoholischView4 = [[UIImageView alloc]initWithImage:alcoholisch4];
UIImageView *alcoholischView5 = [[UIImageView alloc]initWithImage:alcoholisch5];
UIImage *freaky1 = [UIImage imageNamed:#"freaky01.PNG"];
UIImage *freaky2 = [UIImage imageNamed:#"freaky02.PNG"];
UIImage *freaky3 = [UIImage imageNamed:#"freaky03.PNG"];
UIImage *freaky4 = [UIImage imageNamed:#"freaky04.PNG"];
UIImage *freaky5 = [UIImage imageNamed:#"freaky05.PNG"];
UIImageView *freakyView1 = [[UIImageView alloc]initWithImage:freaky1];
UIImageView *freakyView2 = [[UIImageView alloc]initWithImage:freaky2];
UIImageView *freakyView3 = [[UIImageView alloc]initWithImage:freaky3];
UIImageView *freakyView4 = [[UIImageView alloc]initWithImage:freaky4];
UIImageView *freakyView5 = [[UIImageView alloc]initWithImage:freaky5];
NSArray *frisImageArray = [[NSArray alloc]initWithObjects:frisView1,frisView2,frisView3,frisView4,frisView5, nil];
NSArray *alcoholischImageArray = [[NSArray alloc]initWithObjects:alcoholischView1,alcoholischView2,alcoholischView3,alcoholischView4,alcoholischView5, nil];
NSArray *freakyImageArray = [[NSArray alloc]initWithObjects:freakyView1,freakyView2,freakyView3,freakyView4,freakyView5, nil];
NSString *frisFieldName = [[NSString alloc]initWithFormat:#"frisDrankenPlaatjesArray"];
[self setValue:frisImageArray forKey:frisFieldName];
NSString *alcoholischFieldName = [[NSString alloc]initWithFormat:#"alcoholischeDrankenPlaatjesArray"];
[self setValue:alcoholischImageArray forKey:alcoholischFieldName];
NSString *freakyFieldName = [[NSString alloc]initWithFormat:#"freakyDrankenPlaatjesArray"];
[self setValue:freakyImageArray forKey:freakyFieldName];
}
This is the code where I load the images in the pickerView:
-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row
forComponent:(NSInteger)component reusingView:(UIView *)view{
if (component==0) {
NSString *arrayName = [[NSString alloc]initWithFormat:#"alcoholischeDrankenPlaatjesArray"];
NSArray *array = [self valueForKey:arrayName];
return [array objectAtIndex:(row%5)];
}
else if(component==1){
NSString *arrayName = [[NSString alloc]initWithFormat:#"frisDrankenPlaatjesArray"];
NSArray *array = [self valueForKey:arrayName];
return [array objectAtIndex:(row%5)];
}
else if (component==2){
NSString *arrayName = [[NSString alloc]initWithFormat:#"freakyDrankenPlaatjesArray"];
NSArray *array = [self valueForKey:arrayName];
return [array objectAtIndex:(row%5)];
}
else{
return nil;
}
}
this is the code that makes the pickerView spin:
-(IBAction)rotate:(id)sender{
int numInRow =1;
int lastVal = -1;
for (int i=0;i<3; i++) {
int newValue = arc4random()%1000;
if (newValue==lastVal)
numInRow++;
else
numInRow =1;
lastVal=newValue;
[drinkPickerView_ selectRow:newValue inComponent:i animated:YES];
[drinkPickerView_ reloadComponent:i];
}
}
I hope this is enough information and I hope somebody can help me out.

Answer 1

I had a similar problem. I tried retaining the objects, arrays, images but that didn't fix it. Turns out that if I populated the arrays again (ala how you initialized them in the viewDidLoad method) in the -pickerView viewForRow: method then it worked great. Seems inefficient to repopulate the same arrays with every method call but it seemed to do the trick.

Answer 2

I think the problem lays at where you initialize your UIImages:
UIImage *fris1 = [UIImage imageNamed:#"fris01.PNG"]; <-- this is autorelease!
You need to set your UIImages as properties so that they can be retained.
Like so:
#property (nonatomic,retain) UIImage *fris1;
and synthesize them in your .m. and applying the image as:
self.fris1 = [UIImage imageNamed:#"fris01.PNG"];
This way, the UIImage is retained throughout the app life.

Answer 3

This is from UIPickerView.h.
/*
these methods return either a plain UIString, or a view (e.g UILabel) to display the row for the component. for the view versions, we cache any hidden and thus unused views and pass them back for reuse. If you return back a different object, the old one will be released. the view will be centered in the row rect
*/
(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;
(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view;
So when your pickerview tries to show a previously shown uiimageview it releases the previous one. That's why you should create different uiimageview for each component.