ObjectiveC setting image when thread finished - ios

Question

I have a button which I'm trying to set the image for when a thread is finished. My code may seem useless to just change the image button but this is for practise and going onto a bigger thing.
Goal: Set the image for the b0 as button_x.png (found in the project).
Issue: The button image is not changing, if I make a connection between the button found on the storyboard to the viewController button declaration I get a crash with -[UIButton setImage:]: unrecognized selector sent to instance 0x8b4c270.
Thank you.
ViewController.h:
#interface ViewController : UIViewController {
IBOutlet UIButton *b0;
Game *instanceOfGame;
}
#property (nonatomic, strong) UIButton *b0;
#property (nonatomic, strong) Game *instanceOfGame;
#end
ViewController.m:
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
#synthesize instanceOfGame;
#synthesize b0;
static NSString *postName = #"123";
- (void)viewDidLoad
{
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(post:) name:postName object:nil];
instanceOfGame = [[Game alloc] init];
[instanceOfGame start];
}
- (void) post: (NSNotification *) result {
NSNumber *str = [result object];
if (str == 0) {
[self.b0 performSelectorOnMainThread:#selector(setImage: ) withObject:[UIImage imageNamed:#"button_x.png"] waitUntilDone:NO];
}
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
Game.h:
#import <Foundation/Foundation.h>
#interface Game : NSObject
#property (nonatomic, strong) NSNumber *choice;
#property (nonatomic, strong) NSNotificationCenter *ns;
-(void) start;
#end
Game.m:
#import "Game.h"
#implementation Game
NSNotificationCenter *ns;
#synthesize ns;
#synthesize choice;
static NSString *postName = #"123";
-(id) init {
if (self = [super init]) {
ns = [NSNotificationCenter defaultCenter];
}
return self;
}
-(void) start {
[self performSelectorInBackground:#selector(loadData) withObject:Nil];
}
-(void) loadData {
choice = 0;
[ns postNotificationName:postName object:choice];
}
#end

Answer 1

UIButton doesn't have a setImage: function, hence the exception being thrown.
It does have this function though:
- (void)setImage:(UIImage *)image forState:(UIControlState)state
Try replacing:
[self.b0 performSelectorOnMainThread:#selector(setImage: ) withObject:[UIImage imageNamed:#"button_x.png"] waitUntilDone:NO];
With a similar sort of implementation done using GCD calling the correct function:
dispatch_async(dispatch_get_main_queue(), ^{
[self.b0 setImage:[UIImage imageNamed:#"button_x.png"] forState:UIControlStateNormal];
});

Answer 2

#Colin Cornaby saying write.
UIButton doesn't have setImage method.
You can also use the same existing code. just update below line
[self.b0 performSelectorOnMainThread:#selector(setImage: ) withObject:[UIImage imageNamed:#"button_x.png"] waitUntilDone:NO];
as
[self performSelectorOnMainThread:#selector(setImage: ) withObject:[UIImage imageNamed:#"ListDropDown.png"] waitUntilDone:NO];
and then define method setImage:
-(void)setImage:(UIImage *)img
{
[self.bo setImage:img forState:UIControlStateNormal];
}
I hope it will work for you

Answer 3

Try this,
if (str == 0) {
dispatch_sync(dispatch_get_main_queue(), ^{
[self.b0 setImage:[UIImage imageNamed:#"button_x.png"] forState:UIControlStateNormal];
});
}