Question

I am having difficulty in changing the image of my UIButton which is contained within a table view cell. My code as follows:

 // In tableview for cell at rowIndex method
 self.iconBtn = [[UIButton alloc]initWithFrame:CGRectMake(670,10,80, 80)];
            self.iconBtn.tag = kIconValueTag;

 [cell.contentView addSubview:self.iconBtn];

 //Add icon to cell
 UIImage *btnImage = [UIImage imageNamed:@"blank_star.png"];

 [self.iconBtn setImage:btnImage forState:UIControlStateNormal];

 // I am calling method changeIconState after user clicks on icon.
 [self.iconBtn addTarget:self action:@selector(changeIconState) forControlEvents:UIControlEventTouchUpInside];

After the button is pressed, a method outside the table view method is called:

-(void)changeIconState
{
    if (self.iconSelectState == kIconNotSelected) 
    {
        self.iconSelectState = kIconSelected;
    }
    else
    {
        self.iconSelectState = kIconNotSelected;
    }
    [self changeIcon];

}
-(void)changeIcon
{
    if (self.iconSelectState == kIconSelected) 
    {
        UIImage *btnImageHighlighted = [UIImage imageNamed:@"star.png"];
        [self.iconBtn setImage:btnImageHighlighted forState:UIControlStateNormal];
    }
    else
    {
        UIImage *btnImageNormal = [UIImage imageNamed:@"blank_star.png"];
        [self.iconBtn setImage:btnImageNormal forState:UIControlStateNormal];
    }

}

After I run the program, the icon did not change from blank to star as I wanted. It just remained as a blank star. Is there anything I am missing out here?

Answer 1

Why are you managing the image/button state yourself? Why not load the two images for the defined states and let the OS handle it?

 //Add icon to cell
 UIImage *btnImage = [UIImage imageNamed:@"blank_star.png"];
 UIImage *btnImageHighlighted = [UIImage imageNamed:@"star.png"];

 [self.iconBtn setImage:btnImage forState:UIControlStateNormal];
 [self.iconBtn setImage:btnImageHighlighted forState:(UIControlStateHighlighted && UIControlStateSelected)];

If you need to manage your property (iconSelectedState) you can without worrying about the image. Alternatively, you can query the buttons state property to determine which state it is in.