Where to programmatically declare images in Xcode - ios

Question

I'm trying to build a timer app. When the timer hits a certain number (say 5), I want an image to appear. I have the timer working, and the image shows up, but when I declare an if statement to hide the image when the timer has not reached 5, the image shows up anyways. Furthermore, when I declare the UIImageview at the bottom, Xcode reads me the error of "Local declaration of 'images' hides instance variable.
Thank you for any help you can offer! I just started programming.
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController;
-(IBAction)Start:(id)sender; {
Timer = [NSTimer scheduledTimerWithTimeInterval:1 target: self selector:#selector(TimerCount) userInfo: nil repeats:YES];
}
-(void)TimerCount{
CountNumber = CountNumber + 1;
TimerDisplay.text=[NSString stringWithFormat:#"%i", CountNumber];
if(CountNumber < 6) {
imagesx.hidden = YES;
}
if(CountNumber > 6){
imagesx.hidden = NO;
}
}
-(IBAction)UIImage:(id) sender{
self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"Images.jpg"]];
if (CountNumber < 6){
imagesx.hidden = YES;
}
}
-(IBAction)Stop:(id)sender{
[Timer invalidate];
TimerDisplay.text=[NSString stringWithFormat:#"%i", CountNumber];
}
-(IBAction)Reset:(id)sender{
CountNumber = 0;
[Timer invalidate];
CountNumber = 0;
TimerDisplay.text=[NSString stringWithFormat:#"%i", CountNumber];
Timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(TimerCount) userInfo:nil repeats:YES];
[Timer invalidate];
}
-(IBAction)Restart:(id)sender{
CountNumber = 0;
TimerDisplay.text = [NSString stringWithFormat:#"%i", CountNumber];
CountNumber = 0;
Timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:#selector(TimerCount) userInfo:nil repeats: YES];
if (CountNumber < 6){
imagesx.hidden = YES;
}
if (CountNumber > 6){
imagesx.hidden = NO;
}
}
- (void)viewDidLoad{
//create UIImage view programmatically
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
UIImageView *imagesx =[[UIImageView alloc] initWithFrame:CGRectMake(50, 50, 200, 200)];
imagesx.image=[UIImage imageNamed:#"images.jpeg"];
[self.view addSubview:imagesx];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
View Controller.h:
#import <UIKit/UIKit.h>
int CountNumber;
#interface ViewController : UIViewController
{
IBOutlet UILabel *TimerDisplay;
UIImageView *imagesx;
NSTimer *Timer;
}
-(void)TimerCount;
-(IBAction)Start:(id)sender;
-(IBAction)Stop:(id)sender;
-(IBAction)Restart:(id)sender;
#property (strong, nonatomic) IBOutlet UILabel *FirstiPhoneapp;
#property (strong, nonatomic) IBOutlet UILabel *ByJuliaTu;
#property (strong, nonatomic) IBOutlet UIButton *Start;
#property (strong, nonatomic) IBOutlet UIButton *Reset;
#property (strong, nonatomic) IBOutlet UIButton *Terminate;
#property (strong, nonatomic) IBOutlet UIButton *Restart;
#end

Answer 1

You declared your image view as an instance variable with the name "imagesx"
#interface ViewController : UIViewController
{
IBOutlet UILabel *TimerDisplay;
UIImageView *imagesx; <-----your ivar
NSTimer *Timer;
}
So now your view controller has a spot in memory to place an image view.
when viewDidLoad: is called you are doing this:
UIImageView *imagesx =[[UIImageView alloc] initWithFrame:CGRectMake(50, 50, 200, 200)];
This variable (pointer to a UIImageView) has the same name is the instance variable. This will hide access to that ivar and create a new spot in memory for this local version. In other words when you do this in viewDidLoad:
- (void)viewDidLoad{
//create UIImage view programmatically
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
// You are declaring a new image view here with the same name so it "overrides" or hides the ivar by creating a new local one:
UIImageView *imagesx =[[UIImageView alloc] initWithFrame:CGRectMake(50, 50, 200, 200)];
// You are assigning your newly created image view to this local variable
imagesx.image=[UIImage imageNamed:#"Matthijs"];
// adding it to the view, which works but:
[self.view addSubview:imagesx];
// the method returns, this local variable is gone and the ivar is still nil
}
// The ivar is never getting a pointer to your newly created image view. You can't access it after the method returns.
if you put a breakpoint in the timerCount method
Your image view was never set to the ivar (it is nil) so you can't get to it in order to set it to hidden.
The fix is simple. Don't redeclare a new image view in viewDidLoad:, just assign it to your ivar:
imagesx = [[UIImageView alloc] initWithFrame:CGRectMake(50, 50, 200,200)];
Or if you do, declare a new one and change the name:
UIImageView* imageView = [[UIImageView alloc]initWithFrame:CGRectMake(50.0f, 50.0f, 200.0f, 200.0f)];
then assign that to your ivar
imagesx = imageView;

Answer 2

Your code is very hard to follow. You shouldn't create ivars anymore, you can just create a proper for the NSTimer and the UIImageView. Also I'm not sure why you created outlets to the buttons if you're just using the IBActions.
In your viewDidLoad you are redeclaring imagesx and adding it as a subview so when you use the ivar in the timer call, you're actually looking at a nil pointer.
You should declare your NSTimer and the UImageView as properties:
#property (strong, nonatomic) NSTimer * timer;
#property (weak, nonatomic) IBOutlet UIImageView * imageView; // Connect this to an ImageView in the storyboard instead of creating it in code
In your .m file you should access the timer and the image as properties:
self.timer =
self.imageView.image = [UIImage imageNamed:#"..."];