day10
## 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
```
