使用Photos保存图片到自定义相册

//
//  TGSeeBigPicVC.m
//
//  Created by targetcloud on 2017/3/14.
//  Copyright © 2017年 targetcloud. All rights reserved.
//

#import "TGSeeBigPicVC.h"
#import "TGTopicM.h"
#import <SVProgressHUD.h>
#import <Photos/Photos.h>

@interface TGSeeBigPicVC ()<UIScrollViewDelegate>
@property (weak, nonatomic) IBOutlet UIButton *saveBtn;
@property (nonatomic, weak) UIScrollView *scrollV;
@property (nonatomic, weak) UIImageView *imageV;
/** 当前App对应的自定义相册 */
- (PHAssetCollection *)createdCollection;//声明为了点语法 self.createdCollection
/** 返回刚才保存到【相机胶卷】的图片 */
- (PHFetchResult<PHAsset *> *)createdAssets;//声明为了点语法 self.createdAssets
@end

@implementation TGSeeBigPicVC

- (void)viewDidLoad {
    [super viewDidLoad];
    
//    TGLog(@"viewDidLoad %@",NSStringFromCGRect(self.view.bounds))//{{0, 0}, {600, 600}}
    
    UIScrollView *scrollView = [[UIScrollView alloc] init];
//    scrollView.backgroundColor = [UIColor blueColor];
    scrollView.frame = [UIScreen mainScreen].bounds;//不用self.view.bounds，从XIB出来不准
    //如果用self.vew.bounds，那么要加一句 scrollView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight; 但这里仍然不用，因为后面要根据SV做计算，另外的做法也可以把控件的创建移至懒加载,viewDidLayoutSubviews布局控件位置
//    scrollView.frame = self.view.bounds;
//    scrollView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    [scrollView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(back)]];
    [self.view insertSubview:scrollView atIndex:0];//不要挡返回和保存按钮
    _scrollV = scrollView;
    
    UIImageView *imageView = [[UIImageView alloc] init];
    [imageView sd_setImageWithURL:[NSURL URLWithString:self.topic.image1] completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
        if (!image) return;
        _saveBtn.enabled = YES;
    }];
    imageView.width = scrollView.width;
    imageView.height = imageView.width * self.topic.height / self.topic.width;
    imageView.x = 0;
    if (imageView.height > ScreenH) {
        imageView.y = 0;
        scrollView.contentSize = CGSizeMake(0, imageView.height);
    } else {
        imageView.centerY = scrollView.height * 0.5;
    }
    [scrollView addSubview:imageView];
    _imageV = imageView;
    
    CGFloat maxScale = self.topic.width / imageView.width;
    if (maxScale > 1) {
        scrollView.maximumZoomScale = maxScale;
        scrollView.delegate = self;
    }
    
//    TGLog(@"%zd",scrollView.autoresizingMask)//自己代码加的为0 ，如果是XIB加的为18
}

//-(void) viewDidAppear:(BOOL)animated{
//    TGLog(@"viewDidAppear %@",NSStringFromCGRect(self.view.bounds))//{{0, 0}, {414, 736}}
//}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
    return _imageV;
}

- (PHAssetCollection *)createdCollection{
    NSString *title = [NSBundle mainBundle].infoDictionary[(__bridge NSString *)kCFBundleNameKey];
    PHFetchResult<PHAssetCollection *> *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    for (PHAssetCollection *collection in collections) {
        if ([collection.localizedTitle isEqualToString:title]) {
            return collection;
        }
    }
    
    NSError *error = nil;
    __block NSString *createdCollectionID = nil;
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        createdCollectionID = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title].placeholderForCreatedAssetCollection.localIdentifier;
    } error:&error];
    if (error) return nil;
    return [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[createdCollectionID] options:nil].firstObject;
}

- (PHFetchResult<PHAsset *> *)createdAssets{
    NSError *error = nil;
    __block NSString *assetID = nil;
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{//同步
        assetID = [PHAssetChangeRequest creationRequestForAssetFromImage:_imageV.image].placeholderForCreatedAsset.localIdentifier;
    } error:&error];
    if (error) return nil;
    return [PHAsset fetchAssetsWithLocalIdentifiers:@[assetID] options:nil];
}

- (IBAction)back {
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (IBAction)save {
    PHAuthorizationStatus oldStatus = [PHPhotoLibrary authorizationStatus];
    [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
        dispatch_async(dispatch_get_main_queue(), ^{
            if (status == PHAuthorizationStatusDenied) { // 用户拒绝当前App访问相册
                if (oldStatus != PHAuthorizationStatusNotDetermined) {
                    [SVProgressHUD showErrorWithStatus:@"若要保存图片请允许APP访问你的相册！"];
                }
            } else if (status == PHAuthorizationStatusAuthorized) { // 用户允许当前App访问相册
                [self saveImageIntoAlbum];
            } else if (status == PHAuthorizationStatusRestricted) { // 无法访问相册
                [SVProgressHUD showErrorWithStatus:@"因系统原因，无法访问相册！"];
            }
        });
    }];
}

- (void)saveImageIntoAlbum{
    PHFetchResult<PHAsset *> *createdAssets = self.createdAssets;
    if (createdAssets == nil) {
        [SVProgressHUD showErrorWithStatus:@"保存图片失败！"];
        return;
    }

    PHAssetCollection *createdCollection = self.createdCollection;
    if (createdCollection == nil) {
        [SVProgressHUD showErrorWithStatus:@"创建或者获取相册失败！"];
        return;
    }
    
    NSError *error = nil;
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:createdCollection];
        [request insertAssets:createdAssets atIndexes:[NSIndexSet indexSetWithIndex:0]];
    } error:&error];
    if (error) {
        [SVProgressHUD showErrorWithStatus:@"保存图片失败！"];
    } else {
        [SVProgressHUD showSuccessWithStatus:@"保存图片成功！"];
    }
}

/*
 [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.
 */

@end

代码思路

1、首先在info.plist加入key NSPhotoLibraryUsageDescription 和在 .m开始处 #import <Photos/Photos.h>

2、调用过程 save -> saveImageIntoAlbum -> self.createdAssets -> self.createdCollection（使用self. 要在interface声明）