用Photos框架保存图片到相册

2017-01-14 10:45:17来源:http://www.jianshu.com/p/d2bc15374bd1作者:張贺人点击

第七城市


图片来自500px

文 || 张贺


一、保存图片到相机胶卷(Camera Roll)
方法一:利用C语言函数(最快速、最简单的方法)
#import "ViewController.h"
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *Photo;
@end
@implementation ViewController
//保存照片到相册
- (IBAction)savePhoto {
// Adds a photo to the saved photos album. The optional completionSelector should have the form:
// - (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;
//只能保存到相机胶卷(不能保存到自定义相册)
UIImageWriteToSavedPhotosAlbum(self.Photo.image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
if (error) {
//保存失败
}else{
//保存成功
}
}
@end

以上代码运行后程序崩溃。
错误信息:


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.


意思是需要在Info.plist里面增加NSPhotoLibraryUsageDescription这个key来询问用户是否允许访问相册,value为string "我要窥探你的隐私啦~"



示例程序运行截图
方法二:AssetsLibrary框架(iOS9以后废弃,使用Photos框架替代)
方法三:Photos框架

Photos框架须知:
1、PHAsset : 一个PHAsset对象就代表相册中的一张图片或者视频
查 : [PHAsset fetchAsset...]
增删改 :PHAssetChangeRequest(包括图片/视频相关的所有改动操作)
2、PHAssetCollection : 一个PHAssetCollection对象就代表一个相册
查 : [PHAssetCollection fetchAssetCollections...]
增删改 :PHAssetCollectionChangeRequest(包括相册相关的所有改动操作)
3、对相片/相册的任何 [增删改] 操作都必须放到以下两个block中去执行
-[PHPhotoLibrary performChanges:completionHandler:]
-[PHPhotoLibrary performChangesAndWait:error:]
代码:


#import "ViewController.h"
#import <Photos/Photos.h>
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *Photo;
@end
@implementation ViewController
//保存照片到相册
- (IBAction)savePhoto {
//保存照片到相机胶卷
//异步执行修改操作
//PHPhotoLibrary对象就代表着Photos这个应用
[[PHPhotoLibrary sharedPhotoLibrary]performChanges:^{
//默认就把相片保存到了相机胶卷
[PHAssetChangeRequest creationRequestForAssetFromImage:self.Photo.image];
} completionHandler:^(BOOL success, NSError * _Nullable error) {
if (error) {
//保存失败
}else{
//保存成功
}
}];
NSError *error = nil;
//保存照片到相机胶卷
//同步执行修改操作
[[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
//默认就把相片保存到了相机胶卷
[PHAssetChangeRequest creationRequestForAssetFromImage:self.Photo.image];
} error:&error];
if (error) {
//保存失败
}else{
//保存成功
}
}
@end

二、保存图片到自定义相册
第一步:保存图片到相机胶卷
第二步:拥有一个自定义相册
方法一:AssetsLibrary框架(iOS9以后废弃,使用Photos框架替代)
方法二:Photos框架
#import "ViewController.h"
#import <Photos/Photos.h>
@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *Photo;
@end
@implementation ViewController
//创建一个自定义相册
- (IBAction)createdCollection {
//获取应用的名字
NSString *title = [NSBundle mainBundle].infoDictionary[(NSString *)kCFBundleNameKey];
//抓取所有的自定义相册(保证相册只被创建一个)
PHFetchResult<PHAssetCollection *> *collections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
//查找当前APP对应的自定义相册
PHAssetCollection *createdCollection = nil;
for (PHAssetCollection *collection in collections) {
if ([collection.localizedTitle isEqualToString:title]) {
createdCollection = collection;
break;
}
}
//当前APP对应的自定义相册没有被创建过
if (createdCollection == nil) {
NSError *error = nil;
__block NSString *createdCollectionID;
[[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
//创建一个相册,拿到相册的唯一标识符
createdCollectionID = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:title].placeholderForCreatedAssetCollection.localIdentifier;
} error:&error];
//根据相册的唯一标识符拿到相册
createdCollection = [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[createdCollectionID] options:nil].firstObject;
if (error) {
//保存失败
}else{
//保存成功
}
}
}
@end

第三步:添加刚才保存的图片到自定义相册
方法一:AssetsLibrary框架(iOS9以后废弃,使用Photos框架替代)
方法二:Photos框架
//保存照片到自定义相册
- (void)saveImageIntoAlbum{
//保存图片到相机胶卷
PHFetchResult<PHAsset *> *createdAsset = self.createdAsset;
if (createdAsset == nil) {
//保存照片失败
return;
}
//获得相册
PHAssetCollection *collection = self.createdCollection;
if (collection == nil) {
//创建相册失败
return;
}
//把刚才添加到相机胶卷的照片放到自定义相册
NSError *error = nil;
[[PHPhotoLibrary sharedPhotoLibrary]performChangesAndWait:^{
PHAssetCollectionChangeRequest *request = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:collection];
[request insertAssets:createdAsset atIndexes:[NSIndexSet indexSetWithIndex:0]];
} error:&error];
if (error) {
//保存图片失败
return;
}
}


添加图片到自定义的相册

获取以上代码全文点这里




第七城市

最新文章

123

最新摄影

微信扫一扫

第七城市微信公众平台