小贝子编程

使用 QRCode 将图像保存在后台线程的文档目录中



>我正在开发一个应用程序，其中我从iOS库中选择了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，意味着在处理后开始，当我移动到另一个选项卡栏视图时，后台线程停止，我只得到3或4个存储的图像。我使用了不同的后台函数来实现这一点，就像我使用 NSOperationQueue 一样，我也制作了单独的类然后尝试保存但没有成功。我使用过的代码：

- (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。提前感谢！

这是我所说的代码。根据需要进行更改。

后台操作.h 

@protocol BackgroundOperationDelegate <NSObject>
-(void)operationCompleted;
-(void)operationInterrupted;

@end

@interface BackgroundOperation : NSObject

@property (nonatomic, weak) id<BackgroundOperationDelegate> delegate;
+(BackgroundOperation*)sharedInstance;
-(void)saveallD:(NSArray*)info;
@end

后台操作.m

#import "BackgroundOperation.h"
@implementation BackgroundOperation
static BackgroundOperation *_sharedInstance = nil;
+(BackgroundOperation*)sharedInstance{
if(_sharedInstance == nil){
_sharedInstance = [[BackgroundOperation alloc] init];
}
return _sharedInstance;
}

- (id)init {
if(self = [super init]) {
}
return self;
}

-(void)saveallD:(NSArray*)infoArray
{
int i=0;
NSArray *info = [NSArray arrayWithArray:infoArray];
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);
}
}
if(i+1==info.count)
{
[self.delegate operationCompleted];
}
else
{
[self.delegate operationInterrupted];
}
}
@end

您可以在视图控制器中进行如下调用

- (void)elcImagePickerController:(ELCImagePickerController *)picker didFinishPickingMediaWithInfo:(NSArray *)info
{
NSLog(@"%@",info);
[self dismissViewControllerAnimated:YES completion:nil];
[[BackgroundOperation sharedInstance] setDelegate:self];
[[BackgroundOperation sharedInstance] saveallD:info];

}

确保在视图控制器中重写BackgroundOperationDelegate方法，以便在该任务完成后获取回调

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