我在应用程序文档目录中存储了多个图像和视频。我正在以这种方式使用SDWebImage在集合视图中显示图像和视频。
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
AlbumImageCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"AlbumImageCell" forIndexPath:indexPath];
cell.albumImage.image=nil;
cell.layer.shouldRasterize = YES;
cell.layer.rasterizationScale = [UIScreen mainScreen].scale;
if (cell == nil) {
cell = [[[NSBundle mainBundle] loadNibNamed:@"AlbumImageCell" owner:self options:nil] objectAtIndex:0];
}
NSInteger Type=[[[self.arrTbl_Album_Image objectAtIndex:indexPath.row] objectAtIndex:3] intValue];
if (Type==1) {
cell.imgPlay.hidden=YES;
[cell.albumImage setImage:[images objectAtIndex:indexPath.row]];
}else{
cell.imgPlay.hidden=NO;
[cell.albumImage setImage:[images objectAtIndex:indexPath.row]];
}
return cell;
}
此处生成缩略图的代码。
-(void)load_Album_Data{
NSUserDefaults *album_id=[NSUserDefaults standardUserDefaults];
NSInteger Album_id=[album_id integerForKey:@"album_Id"];
//From the query.
NSString *query=[NSString stringWithFormat:@"select * from tbl_Album_Image where album_id='%ld' order by id desc",Album_id];
//Get result.
if (self.arrTbl_Album_Image != nil) {
self.arrTbl_Album_Image=nil;
}
self.arrTbl_Album_Image=[[NSArray alloc]initWithArray:[self.dbManager loadDataFromDB:query]];
dispatch_queue_t myQueue = dispatch_queue_create("MyQueue",NULL);
dispatch_async(myQueue, ^{
for(int i=0;i<self.arrTbl_Album_Image.count;i++)
{
NSInteger AssetType=[[[self.arrTbl_Album_Image objectAtIndex:i] objectAtIndex:3] intValue];
if (AssetType==1) {
//for image
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *inputPath = [[self.arrTbl_Album_Image objectAtIndex:i]objectAtIndex:2 ];
NSString *imageEx=[inputPath pathExtension];
NSString *imageName=[[inputPath lastPathComponent]stringByDeletingPathExtension];
NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@",imageName,imageEx]];
UIImage *img=[UIImage imageWithContentsOfFile:fullPath];
CGFloat scale = MAX(106/img.size.width, 106/img.size.height);
CGFloat width = img.size.width * scale;
CGFloat height = img.size.height * scale;
CGRect imageRect = CGRectMake((106 - width)/2.0f,
(106 - height)/2.0f,
width,
height);
CGSize c=CGSizeMake(106, 106);
UIGraphicsBeginImageContextWithOptions(c, NO, 0);
[img drawInRect:imageRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[images addObject:newImage];
}
else{
//for video
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *inputPath = [[self.arrTbl_Album_Image objectAtIndex:i]objectAtIndex:2 ];
NSString *imageEx=[inputPath pathExtension];
NSString *imageName=[[inputPath lastPathComponent]stringByDeletingPathExtension];
NSString *fullPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@",imageName,imageEx]];
NSURL *videoURL = [NSURL fileURLWithPath:fullPath];
AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:videoURL options:nil];
AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
imageGenerator.appliesPreferredTrackTransform = YES;
NSError *err = NULL;
CMTime time = CMTimeMake(1, 2);
CGImageRef imageRef = [imageGenerator copyCGImageAtTime:time actualTime:NULL error:&err];
UIImage *thumbNailImage = [[UIImage alloc] initWithCGImage:imageRef];
CGFloat scale = MAX(106/thumbNailImage.size.width, 106/thumbNailImage.size.height);
CGFloat width = thumbNailImage.size.width * scale;
CGFloat height = thumbNailImage.size.height * scale;
CGRect imageRect = CGRectMake((106 - width)/2.0f,
(106 - height)/2.0f,
width,
height);
CGSize c=CGSizeMake(106, 106);
UIGraphicsBeginImageContextWithOptions(c, NO, 0);
[thumbNailImage drawInRect:imageRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[images addObject:newImage];
}
dispatch_async(dispatch_get_main_queue(), ^{
//Reload the Image view.
[self.album_ImageView reloadData];
}
});
}
});
}
但问题是我无法更快地加载图像,并且当向上滚动快速发生时应用程序崩溃。而且还没有生成视频图像。 请帮我解决这个问题,并为我提供任何解决方案。 我想在集合视图单元格中加载快速图像。
答案 0 :(得分:1)
而不是将代码设置为此
的代码 [cell.albumImage sd_setImageWithURL:imaURL placeholderImage:[UIImage imageNamed:@"placeholder.png"] options:SDWebImageRefreshCached completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
dispatch_async(dispatch_get_main_queue(), ^{
cell.albumImage.image=image;
});
}];
它会加载更快,甚至可以保存在缓存中
答案 1 :(得分:0)
似乎从照片库中保存图像时,如果需要,应保存完整尺寸,并保存可用于在应用程序中显示的图像的适当缩放版本。如果使用的ALAsset
可能是thumbnail
。
如果这样做,图像加载将很快并且内存使用量最小。
目前,您只是尝试将过多的图像数据加载到内存中,这会花费很长时间,并在应用程序不可避免地耗尽时崩溃。使用设备相机拍摄的图像实际上非常大......