How to make smooth UITableView in objective-C [closed] - ios

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I am working with an IOS application. In my project have several UITableView with many rows, and each row has two images. When I scroll fast then It can't load cells smoothly. How can I scroll smoothly ???
N.B: I don't want to load all rows at a time.
Please Help
Edited:
Here is my code :
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell;
float sca=appDelegate.deviceScaleFloat;
float XOffset=0*sca;
cell = [[UITableViewCell alloc] init];
cell.opaque = YES;
cell.selectionStyle = UITableViewCellSelectionStyleNone;
UIImage *backImg;
backImg= [UIImage imageNamed:[NSString stringWithFormat:#"background-goal-collect%#.png",ipadExtention]];
backImg=[self scaleWithScaleFactor:backImg];
UIImageView *btnBuyImageView=[[UIImageView alloc]initWithImage:backImg];
btnBuyImageView.frame=CGRectMake(XOffset, 0, backImg.size.width, backImg.size.height);
[cell.contentView addSubview: btnBuyImageView];
for (int i=0; i<5 && indexPath.row*5+i<[catFishes count]; i++) {
int productIndex = (int)indexPath.row*5 + i;
DBProductAttributes *productAttributes = [allProductAttributes objectAtIndex:productIndex];
DBProductInfo *productInfo = [catFishes objectAtIndex:productIndex];
UIImage *frameImage = [UIImage imageNamed:[NSString stringWithFormat:#"background-element-%d%#.png",productAttributes.elementid,ipadExtention]];
frameImage=[self scaleWithScaleFactor:frameImage];UIImageView *frameView = [[UIImageView alloc] initWithImage:frameImage];
frameView.frame = CGRectMake((frameImage.size.width*i)+10*sca+5*i*sca, 5*sca , frameImage.size.width, frameImage.size.height);
frameView.userInteractionEnabled=YES;
[cell.contentView addSubview:frameView];
MyTapGestureRecognizer *tapGesture=[[MyTapGestureRecognizer alloc] init];
tapGesture.tag=productIndex;
[tapGesture addTarget:self action:#selector(buttonClicked:)];
[frameView addGestureRecognizer:tapGesture];
NSString *IconStr = [NSString stringWithFormat:#"i%db.png", productInfo.productid];
UIImage *btnImg = [UIImage imageNamed:IconStr];
if(![self isProductPurchesed:productInfo.productid])
{
if([ITIWAppDelegate blackimageforstore]>0)
{
btnImg = [self getBlackAndWhiteVersionOfImage:btnImg];
}
}
UIImageView *imageIconView;
imageIconView = [[UIImageView alloc] initWithImage:btnImg];
imageIconView.frame = CGRectMake(frameView.frame.origin.x+frameImage.size.width-64*sca, frameView.frame.origin.y/*+frameImage.size.height-64*sca*/ , 64*sca, 64*sca);
imageIconView.opaque = YES;
[cell.contentView addSubview:imageIconView];
UILabel *name;
name = [[UILabel alloc] initWithFrame:CGRectMake(frameView.frame.origin.x, frameView.frame.origin.y+62*sca, frameImage.size.width-0*sca, 18.0f*sca)];
name.text = productInfo.product_name;
name.font = [UIFont fontWithName:#"Georgia" size:12.0f*sca];
name.adjustsFontSizeToFitWidth = YES;
name.textAlignment = NSTextAlignmentCenter;
if(![self isProductPurchesed:productInfo.productid])
name.backgroundColor=[UIColor grayColor];
else
name.backgroundColor = [UIColor colorWithRed:colorCodeDragonBook[productAttributes.elementid-1][0]/255.0f green:colorCodeDragonBook[productAttributes.elementid-1][1]/255.0f blue:colorCodeDragonBook[productAttributes.elementid-1][2]/255.0f alpha:1.0f];
name.textColor = [UIColor colorWithWhite:1.0 alpha:1.0];
//name.shadowColor = [UIColor blackColor];
name.autoresizingMask = UIViewAutoresizingFlexibleRightMargin;
[cell.contentView addSubview:name];
NSArray *otherElements = [productAttributes.otherElementid componentsSeparatedByString:#","];
int k=0;
UIImage *habitatFlag = [UIImage imageNamed:[NSString stringWithFormat:#"flag-%d.png",productAttributes.elementid]]; UIImageView *habitatFlagView = [[UIImageView alloc] initWithImage:habitatFlag];
habitatFlagView.frame = CGRectMake(frameView.frame.origin.x-1*sca, frameView.frame.origin.y-1*sca , 15*sca, 22*sca);
[cell.contentView addSubview:habitatFlagView];
k+=15;
for (int i=0; i<[otherElements count]; i++) {
int otherElementid = [[otherElements objectAtIndex:i] intValue];
if(otherElementid==productAttributes.elementid) continue;
UIImage *habitatFlag = [UIImage imageNamed:[NSString stringWithFormat:#"flag-%d.png",otherElementid]]; UIImageView *habitatFlagView = [[UIImageView alloc] initWithImage:habitatFlag];
habitatFlagView.frame = CGRectMake(frameView.frame.origin.x+k*sca-1*sca, frameView.frame.origin.y-1*sca , 15*sca, 22*sca);
[cell.contentView addSubview:habitatFlagView];
k+=15;
}
}
return cell;
}
Problem is occurring when the cells are going to off screen, the tableview release all cells of off screen. And when after that I want to scroll the cells are reloading. I think it is not optimal to load cells. But I don't know how to optimize this.

Answer 1

the best you have to do is load the images asynchronously, and not in the main thread.
If you want, you can use my ImageLoader project : https://github.com/celian-m/ImageLoader/blob/master/ImageLoader.swift
All you have to do is using CMImageView instead of UIImageView.
Then you can do [myImageView assignImageFromUrl:YOUR_URL]
This will load your images in the background thread, in FIFO mode, and save it in memory and disk cache ( i.e. : you need to load each image only 1 time ).

Answer 2

You can make use of SDWebImageCache so that it'll cache the images in disk and the loading of images becomes much faster.

Answer 3

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0ul);
dispatch_async(queue, ^{
//set image here
});
What about setting the image async in the tableview callback:
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
May I ask whether the images are web images or local images?