iOS中获取系统相册中的图片

一.获取单张图片

思路:

1.利用UIImagePickerController可以从系统自带的App(照片\相机)中获得图片
2.设置代理,遵守代理协议

注意

这个

UIImagePickerController

类比较特殊,需要遵守两个代理协议

@interface ViewController () <UIImagePickerControllerDelegate, UINavigationControllerDelegate>

3.实现代理的方法

didFinishPickingMediaWithInfo

- (void)getImageFromIpc
{
// 1.判断相册是否可以打开
if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) return;
// 2. 创建图片选择控制器
UIImagePickerController *ipc = [[UIImagePickerController alloc] init];
/**
typedef NS_ENUM(NSInteger, UIImagePickerControllerSourceType) {
UIImagePickerControllerSourceTypePhotoLibrary, // 相册
UIImagePickerControllerSourceTypeCamera, // 用相机拍摄获取
UIImagePickerControllerSourceTypeSavedPhotosAlbum // 相簿
}
*/
// 3. 设置打开照片相册类型(显示所有相簿)
ipc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
// ipc.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
// 照相机
// ipc.sourceType = UIImagePickerControllerSourceTypeCamera;
// 4.设置代理
ipc.delegate = self;
// 5.modal出这个控制器
[self presentViewController:ipc animated:YES completion:nil];
}

#pragma mark -- <UIImagePickerControllerDelegate>--
// 获取图片后的操作
- (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];
}

二.获取多张图片

思路:

导入头文件

#import <Photos/Photos.h>

PHAsset : 一个资源, 比如一张图片\一段视频
PHAssetCollection : 一个相簿
PHImageManager 图片管理者,是单例,发送请求才能从asset获取图片
PHImageRequestOptions图片请求选项
注意:这个类是iOS8开始推广,iOS9开始废弃之前的方法

系统适配iOS8之前,用下面这个库里面的API

#import <AssetsLibrary/AssetsLibrary.h>

1.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;
// 遍历相机胶卷,获取大图
[self enumerateAssetsInAssetCollection:cameraRoll original:YES];
}

2.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];
}

3.遍历相册

/**
*  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);
}];
}
}

文／船长_（简书作者）

原文链接：http://www.jianshu.com/p/022c41b8f82c

著作权归作者所有，转载请联系作者获得授权，并标注“简书作者”。