【发布时间】：2017-08-18 07:49:02
【问题描述】：
我正在开发一个应用程序，其中我从 iOS 画廊中挑选了 10 张图像，然后生成所有图像的 QRCode，然后使用后台线程将所有内容保存在文档目录中，但问题是当我更改选项卡栏时表示之后当我移动到另一个标签栏视图时处理开始，然后后台线程停止，我只得到 3 或 4 个存储的图像。我使用了不同的背景功能来实现这一点，就像我使用了 NSOperationQueue 一样，我也制作了单独的类，然后尝试保存但没有成功。我用过的代码：
- (void)elcImagePickerController:(ELCImagePickerController *)picker didFinishPickingMediaWithInfo:(NSArray *)info
{
NSLog(@"%@",info);
[self dismissViewControllerAnimated:YES completion:nil];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
[self saveallD:info];
dispatch_async(dispatch_get_main_queue(), ^{
});
});
}
-(void)saveallD:(NSArray*)info
{
// int i=0;
for (NSDictionary *dict in info)
{
if ([dict objectForKey:UIImagePickerControllerMediaType] == ALAssetTypePhoto)
{
// i++;
if ([dict objectForKey:UIImagePickerControllerOriginalImage])
{
UIImage* chosenImage=[dict objectForKey:UIImagePickerControllerOriginalImage];
NSData *imageData = UIImagePNGRepresentation(chosenImage);
CGFloat scale= (100*1024)/(CGFloat)[imageData length]; // For 100KB.
UIImage *small_image=[UIImage imageWithCGImage:chosenImage.CGImage scale:scale orientation:chosenImage.imageOrientation];
NSData *imagefinaldata = UIImageJPEGRepresentation(small_image, scale*1.00);
//UIImage *imgCompressed = [self compressImage:chosenImage];
//NSData *imagefinaldata = UIImagePNGRepresentation(imgCompressed);
BOOL qrcodedetected = NO;
[[NSUserDefaults standardUserDefaults] setObject:imagefinaldata forKey:@"imagesaved"];
// QRCode detector
NSDictionary *detectorOptions = @{ CIDetectorAccuracy : CIDetectorAccuracyHigh };
CIDetector *faceDetector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:detectorOptions];
NSArray *features = [faceDetector featuresInImage:chosenImage.CIImage];
CIQRCodeFeature *faceFeature;
for(faceFeature in features)
{
qrcodedetected = YES;
self.decodedstr = [NSString stringWithFormat:@"%@",faceFeature.messageString];
break;
}
if (!qrcodedetected)
{
int timestamp = [[NSDate date] timeIntervalSince1970];
NSString*selectedFolder=[[NSUserDefaults standardUserDefaults] valueForKey:@"SelectedFolder"];
if ([selectedFolder isEqualToString:@""] || [selectedFolder isKindOfClass:[NSNull class]] || selectedFolder.length==0 )
{
selectedFolder=@"Default";
}
//dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 2), ^{
// time-consuming task
NSLog(@"basepath..%@",[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0]);
NSString *stringPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0]stringByAppendingPathComponent:[NSString stringWithFormat:@"%@",selectedFolder]];
//NSString *QRstringPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0]stringByAppendingPathComponent:@"QRimages"];
if ([[NSFileManager defaultManager] fileExistsAtPath:stringPath])
{
// [imagefinaldata writeToFile:savedImagePath atomically:NO];
// stringPath = [stringPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%d",timestamp]];
NSString *stringPath2 = [stringPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%d",timestamp]];
NSString *savedImagePath = [stringPath2 stringByAppendingPathComponent:[NSString stringWithFormat:@"%d.png",timestamp]];
[self writeImageToFile:stringPath2 :savedImagePath :imagefinaldata];
NSString *savedAudioPath = [stringPath2 stringByAppendingPathComponent:[NSString stringWithFormat:@"%d.m4a",timestamp]];
//NSData*recordedAudioData=[NSData dataWithContentsOfURL:_recorder.url];
if ([autoRecordingCheck isEqualToString:@"ON"])
{
[self writeAudioToFile:stringPath2 :savedAudioPath];
}
}
else
{
[[NSFileManager defaultManager]createDirectoryAtPath:stringPath withIntermediateDirectories:NO attributes:nil error:nil];
NSString *stringPath2 = [stringPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%d",timestamp]];
NSString *savedImagePath = [stringPath2 stringByAppendingPathComponent:[NSString stringWithFormat:@"%d.png",timestamp]];
[self writeImageToFile:stringPath2 :savedImagePath :imagefinaldata];
NSString *savedAudioPath = [stringPath2 stringByAppendingPathComponent:[NSString stringWithFormat:@"%d.m4a",timestamp]];
//NSData*recordedAudioData=[NSData dataWithContentsOfURL:_recorder.url];
if ([autoRecordingCheck isEqualToString:@"ON"])
{
[self writeAudioToFile:stringPath2 :savedAudioPath];
}
// [imagefinaldata writeToFile:savedImagePath atomically:NO];
}
NSString *savedImagePath = [stringPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%d.png",timestamp]];
CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
[filter setDefaults];
NSData *data = [savedImagePath dataUsingEncoding:NSUTF8StringEncoding];
[filter setValue:data forKey:@"inputMessage"];
CIImage *outputImage = [filter outputImage];
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef cgImage = [context createCGImage:outputImage
fromRect:[outputImage extent]];
UIImage *image = [UIImage imageWithCGImage:cgImage
scale:1.0
orientation:UIImageOrientationUp];
// Resize without interpolating
UIImage *resized = [self resizeImage:image
withQuality:kCGInterpolationNone
rate:5.0];
NSData* QRdata = UIImagePNGRepresentation(resized);
NSString *stringPath2 = [stringPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%d",timestamp]];
NSString *savedImagePath2 = [stringPath2 stringByAppendingPathComponent:[NSString stringWithFormat:@"QR%d.png",timestamp]];
[self writeQRToFile:stringPath2 :savedImagePath2 :QRdata];
// [self performSegueWithIdentifier:@"addfilters" sender:nil];
// dispatch_async(dispatch_get_main_queue(), ^{
// [SVProgressHUD dismiss];
// });
//
// });
}
else
{
[self galleryalert];
}
}
}
else
{
NSLog(@"UIImagePickerControllerReferenceURL = %@", dict);
}
}
如果有人有任何类型的解决方案，请告诉我。将不胜感激。提前致谢！
【问题讨论】：
-
可以试试单例
-
@Sanniv：您能否再描述一下。谢谢！
标签： ios objective-c iphone background-process background-thread