iOS表视图滞后问题，我使用调度和保存caching

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { TableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"TableViewCell" forIndexPath:indexPath]; cell.tag = indexPath.row; //cell.imageView.image = nil; // Rounded Rect for cell image CALayer *cellImageLayer = cell.imageView.layer; [cellImageLayer setCornerRadius:25]; [cellImageLayer setMasksToBounds:YES]; [self getImages]; [self storeImages]; UIImage *image =_ResimSonHali[indexPath.row]; dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0); dispatch_async(queue, ^(void) { if (image) { dispatch_async(dispatch_get_main_queue(), ^{ if (cell.tag == indexPath.row) { CGSize itemSize = CGSizeMake(50, 50); UIGraphicsBeginImageContext(itemSize); CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height); [image drawInRect:imageRect]; // cell.ThumbImage.image = image1; cell.imageView.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); [cell setNeedsLayout]; } }); } }); cell.TitleLabel.text = _TarifAdi[indexPath.row]; return cell; } -(void)getImages { NSMutableArray *fuckingArrayYemek = [[NSMutableArray alloc] init]; for (int i=0; i<[_ResimAdiBase count]; i++) { NSString *testString=_ResimAdiBase[i]; NSArray *ImageNames = [testString componentsSeparatedByString:@"."]; [self cacheImage: _ResimAdi[i] : ImageNames[0] ]; [fuckingArrayYemek addObject:ImageNames[0]]; } _ResimSonAdi = fuckingArrayYemek; } -(void) storeImages { NSMutableArray *fuckingArrayYemekName = [[NSMutableArray alloc] init]; for (int i=0; i<[_ResimAdiBase count]; i++) { [fuckingArrayYemekName addObject:[self getCachedImage:_ResimSonAdi[i]]]; } _ResimSonHali = fuckingArrayYemekName; } - (void) cacheImage: (NSString *) ImageURLString : (NSString *)imageName { NSURL *ImageURL = [NSURL URLWithString: ImageURLString]; // Generate a unique path to a resource representing the image you want NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *docDir = [paths objectAtIndex: 0]; NSString *docFile = [docDir stringByAppendingPathComponent: imageName]; // Check for file existence if(![[NSFileManager defaultManager] fileExistsAtPath: docFile]) { // The file doesn't exist, we should get a copy of it // Fetch image NSData *data = [[NSData alloc] initWithContentsOfURL: ImageURL]; UIImage *image = [[UIImage alloc] initWithData: data]; // Is it PNG or JPG/JPEG? // Running the image representation function writes the data from the image to a file if([ImageURLString rangeOfString: @".png" options: NSCaseInsensitiveSearch].location != NSNotFound) { [UIImagePNGRepresentation(image) writeToFile: docFile atomically: YES]; } else if([ImageURLString rangeOfString: @".jpg" options: NSCaseInsensitiveSearch].location != NSNotFound || [ImageURLString rangeOfString: @".jpeg" options: NSCaseInsensitiveSearch].location != NSNotFound) { [UIImageJPEGRepresentation(image, 100) writeToFile: docFile atomically: YES]; } } } - (UIImage *) getCachedImage : (NSString *)imageName { NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString* cachedPath = [documentsDirectory stringByAppendingPathComponent:imageName]; UIImage *image; // Check for a cached version if([[NSFileManager defaultManager] fileExistsAtPath: cachedPath]) { image = [UIImage imageWithContentsOfFile: cachedPath]; // this is the cached image } else { NSLog(@"Error getting image %@", imageName); } return image; } 

当我加载20个数据，我们的表不滞后，但是当我们尝试增加数据大小表视图越来越滞后我们可以certificate这个问题。 首先我们尝试调度，然后我们试图保存图像caching，我们仍然有滞后。 大概，我们处理这个问题约3天。

Answer 1

这是cacheImage（）方法中的问题行，每调用一次“cellForRowAtIndexPath”方法

 NSData *data = [[NSData alloc] initWithContentsOfURL: ImageURL]; 

所以要解决这个问题，请在dispatch_async部分使用这一行。 并根据它更新您的代码。