iOS中获取系统相册中的图片
2018-01-11 本文已影响2216人
黑黝黝的搬砖王
一、调起系统相册选择器
- 1.利用UIImagePickerController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)imagePickerControllerDidCancel:(UIImagePickerController *)picker
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
-(void)showActionSheet
{
UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"选择图片" message:nil preferredStyle:UIAlertControllerStyleActionSheet];
UIAlertAction *action1 = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];
UIAlertAction *action2 = [UIAlertAction actionWithTitle:@"拍照" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
NSString *mediaType = AVMediaTypeVideo;
AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType];
if(authStatus == AVAuthorizationStatusRestricted || authStatus == AVAuthorizationStatusDenied){
// mAlertView(@"", @"请在'设置'中打开相机权限")
return;
}
if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
// mAlertView(@"", @"照相机不可用")
return;
}
UIImagePickerController *vc = [[UIImagePickerController alloc] init];
vc.delegate = self;
vc.allowsEditing = YES;
vc.sourceType = UIImagePickerControllerSourceTypeCamera;
[self presentViewController:vc animated:YES completion:nil];
}];
UIAlertAction *action3 = [UIAlertAction actionWithTitle:@"相册选择" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
UIImagePickerController *vc = [[UIImagePickerController alloc] init];
vc.delegate = self;
vc.allowsEditing = YES;
vc.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
[self presentViewController:vc animated:YES completion:nil];
}];
[alert addAction:action1];
[alert addAction:action2];
[alert addAction:action3];
[self presentViewController:alert animated:YES completion:nil];
}
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
[picker dismissViewControllerAnimated:YES completion:nil];
}
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
{
UIImage *image = [info objectForKey:UIImagePickerControllerEditedImage];
[self.senderBtn setBackgroundImage:image forState:UIControlStateNormal];
//图片在这里压缩一下
NSData *imageData = UIImageJPEGRepresentation(image, 0.5f);
if (imageData.length/1024 > 1024*20)
{
// mAlertView(@"温馨提示", @"请重新选择一张不超过20M的图片");
}
else
{
// _imageType = [NSData typeForImageData:imageData];
// _imageBase64 = [imageData base64EncodedString];
}
[picker dismissViewControllerAnimated:YES completion:nil];
}
二、获取系统相册所有图片
- 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.获得相簿全部原图
- (void)getOriginalImages
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 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.获得相簿中全部缩略图
- (void)getThumbnailImages
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 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
* 遍历相簿中的全部图片
* @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];
options.resizeMode = PHImageRequestOptionsResizeModeFast;
// 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
__weak typeof(self) weakSelf = self;
[[PHImageManager defaultManager] requestImageForAsset:asset targetSize:size contentMode:PHImageContentModeDefault options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
NSLog(@"%@", result);
original ? [weakSelf.photoArray addObject:result] : [weakSelf.photoArray addObject:result];
}];
dispatch_async(dispatch_get_main_queue(), ^{
[weakSelf.showPhotoCollectionView reloadData];
});
}
}
特别注意：
(1).获取全部原图或者全部缩略图时，运行的代码要放在 全局并行队列中
910C933E-8719-4ABD-A24B-547129ED7F7A.png
(2).遍历相册获取到所有图片后再主线程中刷新列表
419D68CD-976F-4F16-B09F-9130240FAF95.png
(3).经过本人测试，放在全局并行队列之后获取相册图片速度都是秒级可以完成，不会阻塞主线程。
