Question

So i have a UIScrollview with UIImageView set with a button, I want to be able to whenever an image is clicked an alertView will pop-up if YES is selected then that image will be deleted in the NSDocumentDirectory. I manage to make the alertView appear but the image isnt deleting because I think is sending a wrong sender or button.tag. Here is my code:

//My scrollView

UIScrollView *scrollView1 = [[UIScrollView alloc] initWithFrame:CGRectMake(0.0f,0.0f,300.0f,134.0f)];
[self.view addSubview:scrollView1];

int row = 0;
int column = 0;
for(int i = 0; i < _thumbs1.count; ++i) {

    UIImage *thumb = [_thumbs1 objectAtIndex:i];
    UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = CGRectMake(column*60+10, row*60+10, 60, 60);
    [button setImage:thumb forState:UIControlStateNormal];
    [button addTarget:self 
               action:@selector(buttonClicked:) 
     forControlEvents:UIControlEventTouchUpInside];
    button.tag = i; 

    [scrollView1 addSubview:button];

    if (column == 4) {
        column = 0;
        row++;
    } else {
        column++;
    }

// Button

- (IBAction)buttonClicked:(id)sender {
    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
    NSInteger slotBG = [prefs integerForKey:@"integerKey"];

    if(slotBG == 1){
        UIAlertView *deleteMessage = [[UIAlertView alloc] initWithTitle:@""
                                                              message:@"DELETE？"
                                                             delegate:self
                                                    cancelButtonTitle:@"NO"
                                                    otherButtonTitles:@"YES", nil];
        [deleteMessage show];          
    }

//for my AlertView

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
    NSString *title = [alertView buttonTitleAtIndex:buttonIndex];

    if([title isEqualToString:@"YES"]){
        // I KNOW THIS IS SOMEWHAT WRONG BECAUSE OF THE SENDER having errors with it
        UIButton *button = (UIButton *)sender;
        [button removeFromSuperview];
        [_images objectAtIndex:button.tag];
        [_images removeObjectAtIndex:button.tag];
        [_images insertObject:[NSNull null] atIndex:button.tag];
        NSFileManager *fileManager = [NSFileManager defaultManager];
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"oneSlotImages%lu.png", button.tag]];
        [fileManager removeItemAtPath: fullPath error:NULL];
        NSLog(@"image removed");
    }

Thanks for the help.

Answer 1

In the clickedButtonAtIndex function you cannot get any reference from your clicked button because it is a callback from UIAlertView. What you can get insider this function are all related to the clicked UIAlertView itself.

If you want to delete selected image, you can first store the pointer or the tag of clicked button in buttonClicked function.

- (IBAction)buttonClicked:(id)sender {
    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
    NSInteger slotBG = [prefs integerForKey:@"integerKey"];

    if(slotBG == 1){
        //  Get the pointer or tag of the clicked button
        _clickedButton = (UIButton *)sender;
        UIAlertView *deleteMessage = [[UIAlertView alloc] initWithTitle:@""
                                                              message:@"DELETE？"
                                                             delegate:self
                                                    cancelButtonTitle:@"NO"
                                                    otherButtonTitles:@"YES", nil];
        [deleteMessage show];        
    }  
}

Then you can use this pointer/tag in the clickedButtonAtIndex function.

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
    NSString *title = [alertView buttonTitleAtIndex:buttonIndex];

    if([title isEqualToString:@"YES"]){
        UIButton *button = _clickedButton;

        [button removeFromSuperview];
        [_images objectAtIndex:button.tag];
        [_images removeObjectAtIndex:button.tag];
        [_images insertObject:[NSNull null] atIndex:button.tag];
        NSFileManager *fileManager = [NSFileManager defaultManager];
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"oneSlotImages%lu.png", button.tag]];
        [fileManager removeItemAtPath: fullPath error:NULL];
        NSLog(@"image removed");
    }

    //  Remember to set it to nil when you finish
    _clickedButton = nil;
}