iOS - 扫描HEIF格式的二维码图片

一、说在前面
iPhone 7 之后系统相机支持HEIF格式的图片，在扫描二维码时，该格式的图片需要转换成JPG格式才能进行扫描成功。
二、思路
用户在打开系统相册选择完一张照片后，要判断该照片是否是HEIF格式，如果是，进行格式转换之后再扫描JPG图片的内容，得到扫描结果。
三、具体实现
因为过程中用到photoKit，因此需要加入该头文件，#import

@protocol TVUImageManagerDelegate <NSObject>
- (void)letQRCodeVCScanQRCodeImageInAlbum:(BOOL)isHEIFFormat;
@end

@interface TVUImageManager : NSObject

@property (strong, nonatomic) UIImage *jpgImage;
@property (strong, nonatomic) UIImage *selectedImage;
@property (strong, nonatomic) PHAsset *selectedAsset;
@property (nonatomic,strong) id  delegate;

+ (TVUImageManager *)defaultManager;
- (void)doSomethingAfterSelectedImage:(NSDictionary *)info;

@end

自定义类：（.mm）

#define IOS9orLater ([UIDevice currentDevice].systemVersion.integerValue >= 9)

@implementation TVUImageManager


#pragma mark - init part
+ (TVUImageManager *)defaultManager
{
    static TVUImageManager *m_manager = nil;
    if (m_manager == nil) {
        m_manager = [[TVUImageManager alloc] init];
    }
    return m_manager;
}

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

    }
    return self;
}


#pragma mark - image format part
- (void)doSomethingAfterSelectedImage:(NSDictionary *)info
{
    [self getSelectedImagePHAsset:info];
    if (self.selectedAsset == nil) {
        log4cplus_error("TVUImageManagerLog", "%s:selected image is null",__func__);
        return;
    }else {
        BOOL isHEIF = [self judgeIfAnImageIsHeifFormat];
        if (isHEIF) {
            log4cplus_error("TVUImageManagerLog", "%s:selected image is HEIF format",__func__);
            [self convertImageFormatFromHeifToJpegAndThenScanTheImage];
        }else {
            log4cplus_error("TVUImageManagerLog", "%s:selected image is not HEIF format",__func__);
            self.selectedImage = (UIImage *)[info objectForKey:UIImagePickerControllerOriginalImage];
            if (self.selectedImage == nil) {
                log4cplus_error("TVUImageManagerLog", "%s:selected image is null",__func__);
                return;
            }
            [self.delegate letQRCodeVCScanQRCodeImageInAlbum:NO];
        }
    }
}

// Choose a picture from the system album
- (void)getSelectedImagePHAsset:(NSDictionary *)info
{
    log4cplus_error("TVUImageManagerLog", "%s:get selected image PHAsset",__func__);
    NSURL *imageAssetUrl = [info objectForKey:UIImagePickerControllerReferenceURL];
    PHFetchResult *fetchResult = [PHAsset fetchAssetsWithALAssetURLs:[NSArray arrayWithObject:imageAssetUrl] options:nil];
    if (fetchResult.count == 0) {
        log4cplus_error("TVUImageManagerLog", "%s:fetchResult's count is 0",__func__);
        return;
    }
    self.selectedAsset = (PHAsset*)fetchResult.firstObject;
}

// Determine if the picture is in HEIF format
- (BOOL)judgeIfAnImageIsHeifFormat
{
    log4cplus_error("TVUImageManagerLog", "%s:begin to judge if an image is HEIF format",__func__);
    __block BOOL isHEIF = NO;
    if (IOS9orLater) {
        NSArray *resourceList = (NSArray *)[PHAssetResource assetResourcesForAsset:self.selectedAsset];
        [resourceList enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
            PHAssetResource *resource = obj;
            NSString *UTI = resource.uniformTypeIdentifier;
            if ([UTI isEqualToString:@"public.heif"] || [UTI isEqualToString:@"public.heic"]) {
                isHEIF = YES;
                *stop = YES;
            }
        }];
    }else {
        NSString *UTI = [self.selectedAsset valueForKey:@"uniformTypeIdentifier"];
        isHEIF = [UTI isEqualToString:@"public.heif"] || [UTI isEqualToString:@"public.heic"];
    }
    return isHEIF;
}

// Convert image format from HEIF to JPEG and then scan the image
- (void)convertImageFormatFromHeifToJpegAndThenScanTheImage
{
    log4cplus_error("TVUImageManagerLog", "%s:begin to convert image format from HEIF to JPEG",__func__);
    [[PHImageManager defaultManager] requestImageDataForAsset:self.selectedAsset options:nil resultHandler:^(NSData * _Nullable imageData, NSString * _Nullable dataUTI, UIImageOrientation orientation, NSDictionary * _Nullable info) {
        CIImage *ciImage = [CIImage imageWithData:imageData];
        CIContext *context = [CIContext context];
        NSData *jpgData = [context JPEGRepresentationOfImage:ciImage colorSpace:ciImage.colorSpace options:@{}];
        self.jpgImage = [UIImage imageWithData:jpgData];
        [self.delegate letQRCodeVCScanQRCodeImageInAlbum:YES];
    }];
}

@end

调用：

#pragma mark UIImagePickerControllerDelegate
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    [self.imageMgr doSomethingAfterSelectedImage:info];
}