ios开发多选照片实现

#import "ViewController.h"
#import <Photos/Photos.h>

@interface ViewController () <UIImagePickerControllerDelegate, UINavigationControllerDelegate>
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (IBAction)selectImage {
    [self getThumbnailImages];
}

/**
 *  获得所有相簿的原图
 */
- (void)getOriginalImages
{
    // 获得所有的自定义相簿
    PHFetchResult<PHAssetCollection *> *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    // 遍历所有的自定义相簿
    for (PHAssetCollection *assetCollection in assetCollections) {
        [self enumerateAssetsInAssetCollection:assetCollection original:YES];
    }
    
    // 获得相机胶卷
    PHAssetCollection *cameraRoll = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil].lastObject;
    [self enumerateAssetsInAssetCollection:cameraRoll original:YES];
}

/**
 *  获得所有相簿中的缩略图
 */
- (void)getThumbnailImages
{
    // 获得所有的自定义相簿
    PHFetchResult<PHAssetCollection *> *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    // 遍历所有的自定义相簿
    for (PHAssetCollection *assetCollection in assetCollections) {
        [self enumerateAssetsInAssetCollection:assetCollection original:NO];
    }
    
    // 获得相机胶卷
    PHAssetCollection *cameraRoll = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil].lastObject;
    [self enumerateAssetsInAssetCollection:cameraRoll original:NO];
}

/**
 *  遍历相簿中的所有图片
 *
 *  @param assetCollection 相簿
 *  @param original        是否要原图
 */
- (void)enumerateAssetsInAssetCollection:(PHAssetCollection *)assetCollection original:(BOOL)original
{
    NSLog(@"相簿名:%@", assetCollection.localizedTitle);
    
    PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
    // 同步获得图片, 只会返回1张图片
    options.synchronous = YES;

    // 获得某个相簿中的所有PHAsset对象
    PHFetchResult<PHAsset *> *assets = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];
    for (PHAsset *asset in assets) {
        // 是否要原图
        CGSize size = original ? CGSizeMake(asset.pixelWidth, asset.pixelHeight) : CGSizeZero;
        
        // 从asset中获得图片
        [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
            NSLog(@"%@", result);
        }];
    }
}

/**
 *  获得相机胶卷中的所有图片
 */
- (void)getImagesFromCameraRoll
{
    // 获得相机胶卷中的所有图片
    PHFetchResult<PHAsset *> *assets = [PHAsset fetchAssetsWithOptions:nil];
    
    __block int count = 0;
    
    for (PHAsset *asset in assets) {
        [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:CGSizeMake(asset.pixelWidth, asset.pixelHeight) contentMode:PHImageContentModeDefault options:nil resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
            NSLog(@"%@ - %zd", result, count++);
        }];
    }
}

/**
 *  利用UIImagePickerController挑选图片
 */
- (void)getImageFromIpc
{
    // UIImagePickerController : 可以从系统自带的App(照片相机)中获得图片

    // 判断相册是否可以打开
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) return;

    UIImagePickerController *ipc = [[UIImagePickerController alloc] init];
    // 打开照片应用(显示所有相簿)
    ipc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    // 打开照片应用(只显示"时刻"这个相簿)
    // ipc.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
    // 照相机
    // ipc.sourceType = UIImagePickerControllerSourceTypeCamera;
    ipc.delegate = self;
    [self presentViewController:ipc animated:YES completion:nil];
}

#pragma mark - <UIImagePickerControllerDelegate>
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
{
    // 销毁控制器
    [picker dismissViewControllerAnimated:YES completion:nil];

    // 设置图片
    self.imageView.image = info[UIImagePickerControllerOriginalImage];
}

@end

总结：1：从相册中选取照片可以利用UIImagePickerController，前提是必须遵守两个协议：

<UIImagePickerControllerDelegate, UINavigationControllerDelegate>但是此种方法只能获取到相册中的一张照片。使用方法如下：1：可以先判断其是否支持相机或是相册，不支持直接return，不执行以下代码 2：创建对象，设置代理，在设置sourceType（注意两种类型的区别），弹出就用presentViewController可以弹出相册，dissmiss返回到应用。实现代理方法获取图片：   self.imageView.image = info[UIImagePickerControllerOriginalImage];3：UIImagePickerController显示中文界面：

1.Project-->Info-->Localizations添加Chinese

2.修改Target-->Info-->Localization native development region ： China 

- (void)getImageFromIpc

{

    // UIImagePickerController : 可以从系统自带的App(照片相机)中获得图片

    // 判断相册是否可以打开

    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) return;

    UIImagePickerController *ipc = [[UIImagePickerController alloc] init];

    // 打开照片应用(显示所有相簿)

    ipc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

    // 打开照片应用(只显示"时刻"这个相簿)

    // ipc.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;

    // 照相机

    // ipc.sourceType = UIImagePickerControllerSourceTypeCamera;

    ipc.delegate = self;

    [self presentViewController:ipc animated:YES completion:nil];

}

#pragma mark - <UIImagePickerControllerDelegate>

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info

{

    // 销毁控制器

    [picker dismissViewControllerAnimated:YES completion:nil];

    // 设置图片

    self.imageView.image = info[UIImagePickerControllerOriginalImage];

}

 2：若是想多选照片：1：可用系统框架：#import <Photos/Photos.h>  2：使用步骤：1：先获得所有相簿，在获得相簿胶卷  

PHAssetCollection

2：遍历相簿数组，得到每一个相册照片PHAsset，再利用PHAsset请求获得每一张照片

3：若想做成系统相簿的样式：1：此界面可采用九宫格搭建，或是采用collection搭建，建议用后者，因为后者可以有循环利用的机制，节省

内存

2：如下界面搭建：可以监听每张图片的点击，当点击到某张图片的时候，将封装好的蒙板和对勾，盖在上面，或是再移除

 3：

## 获得自定义的所有相簿
```objc
// 获得所有的自定义相簿
PHFetchResult<PHAssetCollection *> *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
// 遍历所有的自定义相簿
for (PHAssetCollection *assetCollection in assetCollections) {

}
```

## 获得相机胶卷相簿
```objc
// 获得相机胶卷
PHAssetCollection *cameraRoll = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil].lastObject;
```

## 获得某个相簿的缩略图
```objc
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
// 同步获得图片, 只会返回1张图片
options.synchronous = YES;

// 获得某个相簿中的所有PHAsset对象
PHFetchResult<PHAsset *> *assets = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];
for (PHAsset *asset in assets) {
    CGSize size = CGSizeZero;

    // 从asset中获得图片
    [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
        NSLog(@"%@", result);
    }];
}
```

## 获得某个相簿的原图
```objc
PHImageRequestOptions *options = [[PHImageRequestOptions alloc] init];
// 同步获得图片, 只会返回1张图片
options.synchronous = YES;

// 获得某个相簿中的所有PHAsset对象
PHFetchResult<PHAsset *> *assets = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];
for (PHAsset *asset in assets) {
    CGSize size = CGSizeMake(asset.pixelWidth, asset.pixelHeight);

    // 从asset中获得图片
    [[PHImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
        NSLog(@"%@", result);
    }];
}
```

## 利用UIImagePickerController挑选图片
```objc
// UIImagePickerController : 可以从系统自带的App(照片相机)中获得图片

// 判断相册是否可以打开
if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) return;

UIImagePickerController *ipc = [[UIImagePickerController alloc] init];
// 打开照片应用(显示所有相簿)
ipc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
// 打开照片应用(只显示"时刻"这个相簿)
// ipc.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
// 照相机
// ipc.sourceType = UIImagePickerControllerSourceTypeCamera;
ipc.delegate = self;
[self presentViewController:ipc animated:YES completion:nil];

#pragma mark - <UIImagePickerControllerDelegate>
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
{
    // 销毁控制器
    [picker dismissViewControllerAnimated:YES completion:nil];

    // 设置图片
    self.imageView.image = info[UIImagePickerControllerOriginalImage];
}
```

## NaN错误
- 错误起因:0被当做除数, 比如 10 / 0

## 最简单的方法保存图片到相机胶卷
```objc
UIImageWriteToSavedPhotosAlbum(self.imageView.image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);

/**
 *  通过UIImageWriteToSavedPhotosAlbum函数写入图片完毕后就会调用这个方法
 *
 *  @param image       写入的图片
 *  @param error       错误信息
 *  @param contextInfo UIImageWriteToSavedPhotosAlbum函数的最后一个参数
 */
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    if (error) {
        [SVProgressHUD showErrorWithStatus:@"图片保存失败!"];
    } else {
        [SVProgressHUD showSuccessWithStatus:@"图片保存成功!"];
    }
}
```

## 保存图片到自定义相册
```objc
- (IBAction)save {
    /*
     PHAuthorizationStatusNotDetermined,     用户还没有做出选择
     PHAuthorizationStatusDenied,            用户拒绝当前应用访问相册(用户当初点击了"不允许")
     PHAuthorizationStatusAuthorized         用户允许当前应用访问相册(用户当初点击了"好")
     PHAuthorizationStatusRestricted,        因为家长控制, 导致应用无法方法相册(跟用户的选择没有关系)
     */

    // 判断授权状态
    PHAuthorizationStatus status = [PHPhotoLibrary authorizationStatus];
    if (status == PHAuthorizationStatusRestricted) { // 因为家长控制, 导致应用无法方法相册(跟用户的选择没有关系)
        [SVProgressHUD showErrorWithStatus:@"因为系统原因, 无法访问相册"];
    } else if (status == PHAuthorizationStatusDenied) { // 用户拒绝当前应用访问相册(用户当初点击了"不允许")
        XMGLog(@"提醒用户去[设置-隐私-照片-xxx]打开访问开关");
    } else if (status == PHAuthorizationStatusAuthorized) { // 用户允许当前应用访问相册(用户当初点击了"好")
        [self saveImage];
    } else if (status == PHAuthorizationStatusNotDetermined) { // 用户还没有做出选择
        // 弹框请求用户授权
        [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
            if (status == PHAuthorizationStatusAuthorized) { // 用户点击了好
                [self saveImage];
            }
        }];
    }
}

- (void)saveImage
{
    // PHAsset : 一个资源, 比如一张图片一段视频
    // PHAssetCollection : 一个相簿

    // PHAsset的标识, 利用这个标识可以找到对应的PHAsset对象(图片对象)
    __block NSString *assetLocalIdentifier = nil;

    // 如果想对"相册"进行修改(增删改), 那么修改代码必须放在[PHPhotoLibrary sharedPhotoLibrary]的performChanges方法的block中
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        // 1.保存图片A到"相机胶卷"中
        // 创建图片的请求
        assetLocalIdentifier = [PHAssetCreationRequest creationRequestForAssetFromImage:self.imageView.image].placeholderForCreatedAsset.localIdentifier;
    } completionHandler:^(BOOL success, NSError * _Nullable error) {
        if (success == NO) {
            [self showError:@"保存图片失败!"];
            return;
        }

        // 2.获得相簿
        PHAssetCollection *createdAssetCollection = [self createdAssetCollection];
        if (createdAssetCollection == nil) {
            [self showError:@"创建相簿失败!"];
            return;
        }

        [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
            // 3.添加"相机胶卷"中的图片A到"相簿"D中

            // 获得图片
            PHAsset *asset = [PHAsset fetchAssetsWithLocalIdentifiers:@[assetLocalIdentifier] options:nil].lastObject;

            // 添加图片到相簿中的请求
            PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:createdAssetCollection];

            // 添加图片到相簿
            [request addAssets:@[asset]];
        } completionHandler:^(BOOL success, NSError * _Nullable error) {
            if (success == NO) {
                [self showError:@"保存图片失败!"];;
            } else {
                [self showSuccess:@"保存图片成功!"];;
            }
        }];
    }];
}

/**
 *  获得相簿
 */
- (PHAssetCollection *)createdAssetCollection
{
    // 从已存在相簿中查找这个应用对应的相簿
    PHFetchResult<PHAssetCollection *> *assetCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
    for (PHAssetCollection *assetCollection in assetCollections) {
        if ([assetCollection.localizedTitle isEqualToString:XMGAssetCollectionTitle]) {
            return assetCollection;
        }
    }

    // 没有找到对应的相簿, 得创建新的相簿

    // 错误信息
    NSError *error = nil;

    // PHAssetCollection的标识, 利用这个标识可以找到对应的PHAssetCollection对象(相簿对象)
    __block NSString *assetCollectionLocalIdentifier = nil;
    [[PHPhotoLibrary sharedPhotoLibrary] performChangesAndWait:^{
        // 创建相簿的请求
        assetCollectionLocalIdentifier = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:XMGAssetCollectionTitle].placeholderForCreatedAssetCollection.localIdentifier;
    } error:&error];

    // 如果有错误信息
    if (error) return nil;

    // 获得刚才创建的相簿
    return [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[assetCollectionLocalIdentifier] options:nil].lastObject;
}

- (void)showSuccess:(NSString *)text
{
    dispatch_async(dispatch_get_main_queue(), ^{
        [SVProgressHUD showSuccessWithStatus:text];
    });
}

- (void)showError:(NSString *)text
{
    dispatch_async(dispatch_get_main_queue(), ^{
        [SVProgressHUD showErrorWithStatus:text];
    });
}
```

## Xcode插件的安装路径
```objc
/Users/用户名/Library/Application Support/Developer/Shared/Xcode/Plug-ins
```