CODEWITHSUNDEEP
iosobjective-c
Denis
Denis

Reputation: 71

iOS change BackgroundImage

I want to create a simple checkbox in a tableview. First I create the View in the storyboard and every element get a tag in the cell. Then I coded this in Controller.m

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    ...
    UIButton  *checkbox = (UIButton *)[cell viewWithTag:103];
    checkbox.selected = NO;

    [checkbox setBackgroundImage:[UIImage imageNamed:@"uCheckbox2px"] forState:UIControlStateNormal];

    [checkbox addTarget:self action:@selector(changeState:) forControlEvents:UIControlEventTouchUpInside];
    ...
}

-(void) changeState:(UIButton *)checkbox
{

    checkbox.selected = !checkbox.selected;
    if (checkbox.selected)
        [checkbox setBackgroundImage:[UIImage imageNamed:@"cCheckbox2px"] forState:UIControlStateSelected];
    else
       [checkbox setBackgroundImage:[UIImage imageNamed:@"uCheckbox2px"] forState:UIControlStateNormal];

}

But if I tap on the button the image don't change. Why is this and how I fix it? Thanks for help!

Upvotes: 0

Views: 80

Answers (3)

Lithu T.V
Lithu T.V

Reputation: 20021

Make it like this

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    ...
    UIButton  *checkbox = (UIButton *)[cell viewWithTag:103];

    [checkbox setBackgroundImage:[UIImage imageNamed:@"uCheckbox2px"] forState:UIControlStateNormal];
    [checkbox setBackgroundImage:[UIImage imageNamed:@"cCheckbox2px"] forState:UIControlStateSelected];

    [checkbox addTarget:self action:@selector(changeState:) forControlEvents:UIControlEventTouchUpInside];
    ...
}

-(void) changeState:(UIButton *)checkbox
{

    checkbox.selected = !checkbox.selected;
}

Upvotes: 1

manujmv
manujmv

Reputation: 6445

This is because everytime calling cellForRowAtIndexPath: checkbox.selected = NO; will make the selected property FALSE. So after that, in the changeState:,

checkbox.selected = !checkbox.selected;

will change the selected property to TRUE. So whenever you tap the button, selected property becomes TRUE only. So move checkbox.selected = NO; to inside of if(cell == nil) condition

Upvotes: 1

HRM
HRM

Reputation: 2127

I guess the code you have given in your button tap event is not needed. Only changing the state is enough. 

    if (checkbox.selected)
        [checkbox setBackgroundImage:[UIImage imageNamed:@"cCheckbox2px"] forState:UIControlStateSelected];
    else
       [checkbox setBackgroundImage:[UIImage imageNamed:@"uCheckbox2px"] forState:UIControlStateNormal];

But you need to specify the image for both states (UIControlStateSelected and UIControlStateNormal) in your cellForRowAtIndexPath.

Upvotes: 0

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