UIImage replaces with another UIImage not Smooth

Question

I'm working on a project where I'm rendering Images from UIWebView and then showing into a tableView with custom UITableViewCell. When UITableView presents first time...there is no rendered images to display, so I'm displaying a default image(i.e. icon-thumb.png) in the cell. Once Images rendered I'm reloading UITableView. I'm doing this as below…

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
        NSString *reuseIdentifier = @"CustomTableViewID";             CustomTableViewCell  *cell = [tableView dequeueReusableCellWithIdentifier:reuseIdentifier];
        if (cell == nil)
        {
            cell = (CustomTableViewCell *)[[[NSBundle mainBundle] loadNibNamed:@"CustomTableViewCell" owner:nil options:nil] objectAtIndex:0];
        }

        CGRect mainImageViewFrame = CGRectMake(9, 31, 202, 171);
        cell.mainImageView.frame = mainImageViewFrame;

        [cell setBackgroundColor:[UIColor clearColor]];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
        cell.transform = CGAffineTransformMakeRotation(M_PI * 0.5);

        cell.slideNumberLbl.textColor = [UIColor whiteColor];
        cell.slideNumberLbl.backgroundColor = [UIColor grayColor];
        cell.slideNumberLbl.layer.cornerRadius = 5.0;
        cell.slideNumberLbl.alpha = 0.5;
        [cell.slideNumberLbl setTextAlignment:NSTextAlignmentCenter];
        cell.slideNumberLbl.text = [NSString stringWithFormat:@"%d",indexPath.row+1];

        [cell.mainImageView setBackgroundColor:[UIColor clearColor]];

        [cell.reflectionImageView setContentMode:UIViewContentModeScaleToFill];
        cell.reflectionImageView.alpha = 0.15;

        NSFileManager *manager = [NSFileManager defaultManager];
        NSString *thumbImagepath = [self.storageDirPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%d_thumb%@",indexPath.row, Image_Extension_JPG]];

        if([manager fileExistsAtPath:thumbImagepath]){
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
                __block UIImage *img = [UIImage imageWithContentsOfFile:thumbImagepath];
                dispatch_async(dispatch_get_main_queue(), ^{

                    CGRect mainImageViewFrame = CGRectMake(9, 31, 202, 171);
                    cell.mainImageView.frame = mainImageViewFrame;
                    cell.mainImageView.image = img;
                    [cell.mainImageView setContentMode:UIViewContentModeScaleAspectFit];
                    img = nil;
                    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
                        __block UIImage *reflectionImg = [self reflectedImage:cell.mainImageView withHeight:cell.mainImageView.frame.size.height];
                        dispatch_async(dispatch_get_main_queue(), ^{
                            cell.reflectionImageView.image = reflectionImg;
                            reflectionImg = nil;
                        });
                    });
                });
            });
        }
        else{
            CGRect mainImageViewFrame = CGRectMake(9, 31, 202, 171);
            mainImageViewFrame.origin.y = mainImageViewFrame.origin.y+10;
            mainImageViewFrame.size.height = mainImageViewFrame.size.height-20;
            cell.mainImageView.frame = mainImageViewFrame;

            [cell.mainImageView setContentMode:UIViewContentModeCenter];
            [cell.mainImageView setBackgroundColor:[UIColor whiteColor]];
            cell.mainImageView.image = [UIImage imageNamed:@"icon-thumb.png"];
            [cell.reflectionImageView setBackgroundColor:[UIColor whiteColor]];
            [cell.reflectionImageView setImage:[UIImage imageNamed:@"reflection_temp.png"]];
        }

        return cell;
    }

The problem is, when the default image (i.e. icon-thumb.png) gets replace with the real image once real images rendering done..the replacement is not smooth, the Image replaces with flash/or all of sudden but it need to be very smooth...any suggestion, thanks in advance.

http://stackoverflow.com/questions/7638831/fade-dissolve-when-changing-uiimageviews-image/38350024#38350024 — Kumar KL, Jul 13 '16 at 11:28

score 0 · Answer 1 · answered Mar 25 '14 at 08:56

0

It may be stupid answer but didn't you try to use an animation for this ?

like this :

        [UIView animateWithDuration:duration animations:^{
            } completion:^(BOOL finished) {
            }
        }];

answered Mar 25 '14 at 08:56

Clad Clad

2,653
1
20
32

score 0 · Accepted Answer · answered Mar 25 '14 at 09:40

0

you can use CATransition for example

 CATransition *transition = [CATransition animation];
    transition.duration = 0.2;//duration
    transition.type = kCATransitionFade; //choose your animation
    [yourCell.layer addAnimation:transition forKey:nil];
    [yourCell.mainimageview setImage:img];

answered Mar 25 '14 at 09:40

savana

221
2
5

savana thanks for your reply but I've solved issue. I found http://stackoverflow.com/questions/2834573/how-to-animate-the-change-of-image-in-an-uiimageview . but your answer also I'll accept since this also will work. – Suryakant Sharma Mar 25 '14 at 11:04

score 0 · Answer 3 · answered Jun 17 '16 at 22:02

I would do something like the following :

[UIView transitionWithView:cell.mainImageView
                  duration:0.2f
                   options:UIViewAnimationOptionTransitionCrossDissolve
                animations:^{
                    cell.mainImageView.image = [UIImage imageNamed:@"icon-thumb.png"];
                } completion:nil];

I find that approach slightly more elegant.

UIImage replaces with another UIImage not Smooth

3 Answers3