PhotoKit保存图片到相册

我们分为几个步骤学习

准备工作

1. 配置info.plist
2. 引入头文件

在开始开发之前需要进行info.plist的配置，如果不进行配置会抛错。

NSPhotoLibraryAddUsageDescription
需要您同意使用相册权限保存图片
NSPhotoLibraryUsageDescription
需要您同意使用相册权限保存图片

2019-12-23 09:13:56.301622+0800 ZucheDemo[920:649891] [access] This app has crashed because it attempted to access privacy-sensitive data without a usage description. The app's Info.plist must contain an NSPhotoLibraryUsageDescription key with a string value explaining to the user how the app uses this data.

在开发之前我们导入头文件

#import 

存储一个图片到相册胶卷

此方法可以保存一张图片到相机胶卷。

/// 保存图片到相机胶卷
- (void)saveImageToCameraRoll:(UIImage *)image {
    //保存图片到【相机胶卷】
    [[PHPhotoLibrary sharedPhotoLibrary]performChanges:^{
        //异步执行修改操作
        [PHAssetChangeRequest creationRequestForAssetFromImage:image];
    } completionHandler:^(BOOL success, NSError * _Nullable error) {
        if (error) {
            NSLog(@"%@",@"保存失败");
        } else {
            NSLog(@"%@",@"保存成功");
        }
    }];
}

创建一个相册（以应用名册命名）

首先我们看如何创建一个相册

/// 创建以app名字命名的相册
- (void)createNewCollection {
    NSError *error = nil;
    [[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
        //获取app名字
        NSString *title = [NSBundle mainBundle].infoDictionary[(__bridge NSString*)kCFBundleNameKey];
        //创建一个【自定义相册】
        [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title];
        
    } error:&error];
}

但是这么简单的创建相册，一般不符合需求，一般我们需要先查看是否已经存在同名相册。

/// 查看是否创建了以APP命名的相册
- (PHAssetCollection *)checkLocalCollection {
    NSString *title = [NSBundle mainBundle].infoDictionary[(__bridge NSString*)kCFBundleNameKey];
    return [self checkCollection:title];
}

/// 查看是否创建了以此名字命名的相册
/// @param title 相册名字
- (PHAssetCollection *)checkCollection:(NSString *)title {
    //查询所有【自定义相册】
    PHFetchResult *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    PHAssetCollection *createCollection = nil;
    for (PHAssetCollection *collection in collections) {
        if ([collection.localizedTitle isEqualToString:title]) {
            createCollection = collection;
            break;
        }
    }
    return createCollection;
}

所以我们需要先查看是否存在同名相册，之后再进行创建相册

/// 创建一个以APP名字命名的相册,如果不存在
- (void)createNewCollectionIfNotExist {
    
    NSString *title = [NSBundle mainBundle].infoDictionary[(__bridge NSString*)kCFBundleNameKey];
    
    PHAssetCollection *createCollection = [self checkCollection:title];
    
    if (createCollection == nil) {
        //当前对应的app相册没有被创建
        //创建一个【自定义相册】
        NSError *error = nil;
        [[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
            //创建一个【自定义相册】
            [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title];
        } error:&error];
        
    }
    
}

保存图片到创建的相册

/// 保存图片到自己创建的相册
/// @param image 图片
- (void)savePhotoToAlbum:(UIImage *)image {
    // 1.先保存图片到【相机胶卷】
    /// 同步执行修改操作
    NSError *error = nil;
    
    __block PHObjectPlaceholder *placeholder = nil;
    
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
       placeholder =  [PHAssetChangeRequest creationRequestForAssetFromImage:image].placeholderForCreatedAsset;
    } error:&error];
    
    if (error) {
        NSLog(@"保存失败");
        return;
    }
    
    // 2.查看是否拥有一个以APP名称命名的相册
    PHAssetCollection * assetCollection = [self checkLocalCollection];
    
    if (assetCollection == nil) {
        NSLog(@"获取相册失败");
        return;
    }
    
    // 3.将刚才保存到【相机胶卷】里面的图片引用到【自定义相册】
    [[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
        PHAssetCollectionChangeRequest *requtes = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:assetCollection];
        [requtes addAssets:@[placeholder]];
    } error:&error];
    
    if (error) {
        NSLog(@"保存图片失败");
    } else {
        NSLog(@"保存图片成功");
    }
}

查找图片并显示

/// 查找图片
- (void)fetchPhotoFromLocalCollection {
    
    PHAssetCollection *assetCollection =  [self checkLocalCollection];
    
    if (assetCollection == nil) {
        NSLog(@"获取相册失败");
        return;
    }
    
    PHFetchResult *results = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];
    
    if (results.count > 0) {
        
        __weak typeof(self) weakSelf = self;
        //获取最后一个图片
        PHAsset *asset = results.lastObject;
        //获取显示图片控件的大小
        CGSize size = CGSizeMake(CGRectGetWidth(self.imageView.bounds), CGRectGetHeight(self.imageView.bounds));
        //调用转换方法
        [self imageWithAsset:asset size:size resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
            if (result) {
                NSLog(@"%@",info);
                weakSelf.imageView.image = result;
            }
            else {
                NSLog(@"转换图片失败");
            }
        }];
    }
    
}

/// asset转成为image
/// @param asset asset description
/// @param size 图片尺寸
/// @param resultHandler 结果回调
- (void)imageWithAsset:(PHAsset *)asset size:(CGSize)size resultHandler:(void(^)(UIImage * _Nullable result, NSDictionary * _Nullable info))resultHandler {
    //option的设置
    PHImageRequestOptions *option = [[PHImageRequestOptions alloc] init];
    option.resizeMode = PHImageRequestOptionsResizeModeNone;
    
    [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:(PHImageContentModeAspectFit) options:option resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
        
        if (resultHandler) {
            resultHandler(result,info);
        }
        
    }];
    
}

从相册中删除图片

/// 删除图片
- (void)deletePhotoFromLocalCollection {
    
    PHAssetCollection *assetCollection =  [self checkLocalCollection];
    
    PHFetchResult *results = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];
    
    if (results.count > 0) {
        
        NSError *error = nil;
        
        [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
            
            //删除时候需要传入一个PHFetchResulth或者一个数组,遵守这个协议的类
            
            //删除最后一张
            //[PHAssetChangeRequest deleteAssets:@[results.lastObject]];
            
            //删除整个相册内的所有图片
            [PHAssetChangeRequest deleteAssets:results];
            
        } error:&error];
    }
    
}