我已经从图库中获取了图像和视频，当视频和图像的数量最少时它工作正常，但是当图像和视频的数量很大时，它会阻塞主线程。
-(void)viewDidAppear:(BOOL)animated{
[NSThread sleepForTimeInterval:1];
// call the same method on a background thread
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self getAllVideosAndImages];
});
}
从 Assets 中获取图像和视频
-(void)getAllVideosAndImages{
NSMutableArray *assetGroups = [[NSMutableArray alloc] init];
assetGroups = [[NSMutableArray alloc] init];
library = [[ALAssetsLibrary alloc] init];
NSUInteger groupTypes = ALAssetsGroupAll;
void (^assetEnumerator)
( ALAsset *, NSUInteger, BOOL *) = ^(ALAsset *result, NSUInteger index, BOOL *stop) {
if(result != nil) {
if([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypeVideo]||[[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {
ALAssetRepresentation *rep = [result defaultRepresentation];
CGImageRef iref = [rep fullResolutionImage];
if (iref) {
//GET DATE
NSDate *myDate = [result valueForProperty:ALAssetPropertyDate];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"MMM dd,YYYY"];
NSString *realDateStr = [dateFormatter stringFromDate:myDate];
//GET IMG AND VIDEO
UIImage *largeimage = [UIImage imageWithCGImage:iref];
NSData *webData = UIImagePNGRepresentation(largeimage);
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *localFilePath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"img%zd.mov",imgName]];
imgName=imgName+1;
[webData writeToFile:localFilePath atomically:YES];
Para_ImageSet *objImgSet=[Para_ImageSet new];
objImgSet.imagePath=localFilePath;
objImgSet.imageDate=realDateStr;
// [yArrayOfAllImges addObject:objImgSet];
if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypeVideo]) {
objImgSet.is_video=YES;
}
else
{
objImgSet.is_video=NO;
}
if ([tempDate isEqualToString:@""]) {
yArrayOfImagesWithDate=[NSMutableArray new];
[yArrayOfImagesWithDate addObject:objImgSet];
tempDate=realDateStr;
}else
{
//GATE IMAGE COUNT
if ([realDateStr isEqualToString:tempDate]) {
//DO NOTHING
[yArrayOfImagesWithDate addObject:objImgSet];
}
else
{
[yArrayOFNNestedImgs addObject:yArrayOfImagesWithDate];
NSLog(@" ----------ImagesWithDate =%zd, %@",yArrayOfImagesWithDate.count,tempDate);
yArrayOfImagesWithDate=[NSMutableArray new];
[yArrayOfImagesWithDate addObject:objImgSet];
tempDate=realDateStr;
}
}
}
}
}
[self.tableView reloadData];
};
void (^ assetGroupEnumerator) ( ALAssetsGroup *, BOOL *)= ^(ALAssetsGroup *group, BOOL *stop) {
if(group != nil) {
[group enumerateAssetsUsingBlock:assetEnumerator];
[assetGroups addObject:group];
// NSNumber *countObj = [NSNumber numberWithInt:count];
NSLog(@" ----------ImagesWithDate =%zd, %@",yArrayOfImagesWithDate.count,tempDate);
[yArrayOFNNestedImgs addObject:yArrayOfImagesWithDate];
NSLog(@" ----------Count =%zd",yArrayOFNNestedImgs.count);
[NSThread sleepForTimeInterval:10];
// update UI on the main thread
dispatch_async(dispatch_get_main_queue(), ^{
[self.tableView reloadData];
});
}
};
[library enumerateGroupsWithTypes:groupTypes
usingBlock:assetGroupEnumerator
failureBlock:^(NSError *error) {NSLog(@"A problem occurred");}];
}
请建议..提前致谢
最佳答案
[NSThread sleepForTimeInterval:1]; 正在阻塞主线程一秒钟。不需要。
你可以使用[self performSelectorInBackground:@selector(getAllVideosAndImages) withObject:nil];
还有，先把[self.tableView reloadData];包起来
dispatch_async(dispatch_get_main_queue(), ^{
...
});也是
关于ios - 在 iOS 中如何在从 Assets 中获取图像和视频时应用延迟加载？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32400646/