随着iOS10的推出，Xcode 8 最低支持iOS 8.0，PhotoKit可以完全替代ALAssetsLibrary来管理相册资源。本文主要介绍PhotoKit的基本使用,做一个简易的相片选择器。
一、基本概念：
PHAsseet:代表照片库中的一个资源，跟 ALAsset 类似，通过 PHAsset 可以获取和保存资源; PHFetchOptions:获取资源时的参数，可以传nil，即使用系统默认值； PHFetchResult:表示一系列的资源集合，也可以是相册的集合； PHAssetCollection:表示一个相册或者一个时刻，或者是一个「智能相册(系统提供的特定的一系列相册，例如：最近删除，视频列表，收藏等等); PHCollectionList:表示一组PHCollection,而它本身也是一个PHCollection,因此PHCollection作为一个集合，可以包含其他集合，例如：照片 - 时刻 - 精选 - 年度； PHImageManager:用于处理资源的加载，加载图片的过程带有缓存处理，可以通过传入一个 PHImageRequestOptions 控制资源的输出尺寸等规格; PHImageRequestOptions:如上面所说，控制加载图片时的一系列参数。
二、PhotoKit的基本使用：
######为便于使用，封装一个单例类PhotoCatcherManager，实现以下方法： 1.获取全部相册：
-(NSMutableArray<PHAssetCollection*> *)getPhotoListDatas{
NSMutableArray *dataArray = [NSMutableArray array];
//获取资源时的参数，为nil时则是使用系统默认值
PHFetchOptions *fetchOptions = [[PHFetchOptions alloc]init];
//列出所有的智能相册
PHFetchResult *smartAlbumsFetchResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:fetchOptions];
[dataArray addObject:[smartAlbumsFetchResult objectAtIndex:0]];
//列出所有用户创建的相册
PHFetchResult *smartAlbumsFetchResult1 = [PHAssetCollection fetchTopLevelUserCollectionsWithOptions:fetchOptions];
for (PHAssetCollection *sub in smartAlbumsFetchResult1) {
[dataArray addObject:sub];
}
return dataArray;
}
2.获取一个相册的结果集(按时间排序)
//获取某个相册的结果集
-(PHFetchResult<PHAsset *> *)getFetchResult:(PHAssetCollection *)assetCollection ascend:(BOOL)ascend{
PHFetchOptions *options = [[PHFetchOptions alloc] init];
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 9.0f) {
options.includeAssetSourceTypes = PHAssetSourceTypeUserLibrary;
}
//时间排序
options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:ascend]];
PHFetchResult *allPhotos = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];
return allPhotos;
}
3.获取某个类型的结果集(按时间排序)
+ (PHFetchResult<PHAsset *> *)getFetchResultWithMediaType:(PHAssetMediaType)mediaType ascend:(BOOL)ascend{
PHFetchOptions *options = [[PHFetchOptions alloc] init];
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 9.0f) {
options.includeAssetSourceTypes = PHAssetSourceTypeUserLibrary;
}
options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:ascend]];
return [PHAsset fetchAssetsWithMediaType:mediaType options:options];
}
4.获取系统相册CameraRoll 的结果集(按时间排序)
-(PHFetchResult<PHAsset *> *)getCameraRollFetchResulWithAscend:(BOOL)ascend{
//获取系统相册CameraRoll 的结果集
PHFetchOptions *fetchOptions = [[PHFetchOptions alloc]init];
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 9.0f) {
fetchOptions.includeAssetSourceTypes = PHAssetSourceTypeUserLibrary;
}
fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:ascend]];
PHFetchResult *smartAlbumsFetchResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumUserLibrary options:nil];
PHFetchResult *fetch = [PHAsset fetchAssetsInAssetCollection:[smartAlbumsFetchResult objectAtIndex:0] options:fetchOptions];
return fetch;
}
5.获取单张高清图,progressHandler为从iCloud下载进度
-(void)getImageHighQualityForAsset:(PHAsset *)asset progressHandler:(void(^)(double progress, NSError * error, BOOL *stop, NSDictionary * info))progressHandler resultHandler:(void (^)(UIImage* result, NSDictionary * info))resultHandler{
CGSize imageSize = [self imageSizeForAsset:asset];
PHImageRequestOptions * options = [[PHImageRequestOptions alloc] init];
//设置该模式，若本地无高清图会立即返回缩略图，需要从iCloud下载高清，会再次调用resultHandler返回下载后的高清图
options.deliveryMode = PHImageRequestOptionsDeliveryModeOpportunistic;
options.resizeMode = PHImageRequestOptionsResizeModeFast;
options.networkAccessAllowed = YES;
options.progressHandler = ^(double progress, NSError *__nullable error, BOOL *stop, NSDictionary *__nullable info){
if (progressHandler) {
dispatch_async(dispatch_get_main_queue(), ^{
progressHandler(progress,error,stop,info);
});
}
};
[[PHCachingImageManager defaultManager] requestImageForAsset:asset targetSize:imageSize contentMode:PHImageContentModeAspectFill options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
//判断高清图
// BOOL downloadFinined = ![[info objectForKey:PHImageCancelledKey] boolValue] && ![info objectForKey:PHImageErrorKey] && ![[info objectForKey:PHImageResultIsDegradedKey] boolValue];
if (result && resultHandler) {
resultHandler(result,info);
}
}];
}
私有方法，根据屏幕获取图片的大小
-(CGSize)imageSizeForAsset:(PHAsset *)asset{
CGFloat photoWidth = [UIScreen mainScreen].bounds.size.width;
CGFloat multiple = [UIScreen mainScreen].scale;
CGFloat aspectRatio = asset.pixelWidth / (CGFloat)asset.pixelHeight;
CGFloat pixelWidth = photoWidth * multiple;
CGFloat pixelHeight = pixelWidth / aspectRatio;
return CGSizeMake(pixelWidth, pixelHeight);
}
6.获取单张缩略图
-(void)getImageLowQualityForAsset:(PHAsset *)asset targetSize:(CGSize)targetSize resultHandler:(void (^)(UIImage* result, NSDictionary * info))resultHandler{
[[PHCachingImageManager defaultManager] requestImageForAsset:asset targetSize:targetSize contentMode:PHImageContentModeAspectFill options:nil resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
if (result && resultHandler) {
resultHandler(result,info);
}
}];
}
7.同时获取多张图片(高清)，全部为高清图resultHandler才执行，需要从iCloud下载时progressHandler提供每张进度（P.S:内部压缩图片方法实现）
-(void)getImagesForAssets:(NSArray<PHAsset *> *)assets progressHandler:(void(^)(double progress, NSError * error, BOOL *stop, NSDictionary * info))progressHandler resultHandler:(void (^)(NSArray<NSDictionary *> *))resultHandler{
NSMutableArray * callBackPhotos = [NSMutableArray array];
//此处在子线程中执行requestImageForAsset原因：options.synchronous设为同步时,options.progressHandler获取主队列会死锁
NSOperationQueue * queue = [[NSOperationQueue alloc] init];
queue.maxConcurrentOperationCount = 1;
for (PHAsset * asset in assets) {
CGSize imageSize = [self imageSizeForAsset:asset];
PHImageRequestOptions * options = [[PHImageRequestOptions alloc] init];
// options.deliveryMode = PHImageRequestOptionsDeliveryModeFastFormat;
options.resizeMode = PHImageRequestOptionsResizeModeExact;
options.networkAccessAllowed = YES;
//同步保证取出图片顺序和选择的相同，deliveryMode默认为PHImageRequestOptionsDeliveryModeHighQualityFormat
options.synchronous = YES;
options.progressHandler = ^(double progress, NSError *__nullable error, BOOL *stop, NSDictionary *__nullable info){
dispatch_async(dispatch_get_main_queue(), ^{
progressHandler(progress,error,stop,info);
});
};
NSBlockOperation * op = [NSBlockOperation blockOperationWithBlock:^{
[[PHCachingImageManager defaultManager] requestImageForAsset:asset targetSize:imageSize contentMode:PHImageContentModeAspectFill options:options resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
//resultHandler默认在主线程，requestImageForAsset在子线程执行后resultHandler变为在子线程
if (result) {
//压缩图片，可用于上传
NSData * data = [UIImage resetSizeOfImageData:result compressQuality:0.2];
UIImage * image = [UIImage imageWithData:data];
NSDictionary * dic = @{EEPhotoImage:image,EEPhotoName:asset.localIdentifier};
[callBackPhotos addObject:dic];
if (resultHandler && callBackPhotos.count == assets.count) {
dispatch_async(dispatch_get_main_queue(), ^{
resultHandler(callBackPhotos);
});
}
}
}];
}];
[queue addOperation:op];
}
}
8.获取相册授权状态
+(void)requestAuthorizationHandler:(void(^)(BOOL isAuthorized))handler {
if (handler) {
[PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
dispatch_async(dispatch_get_main_queue(), ^{
if (status == PHAuthorizationStatusAuthorized) {
handler(YES);
}else{
handler(NO);
}
});
}];
}
}
三、创建相片选择器：
1.先看效果图（注意同时拉取多张大图时内存处理）
主要包含以下几点：
- ViewControllerA含有一个UITextView，我们从相册选取一张或多张图片让其展示。
- ViewControllerB是相片选择界面，有UICollectionView构成，展示的是相册图片缩略图。
- ViewControllerB界面点击图片可查看该图片高清图。
######2.实现 2.1. ViewControllerA.m
- (void)viewDidLoad {
[super viewDidLoad];
self.textView.textContainerInset = UIEdgeInsetsZero;
self.textView.textContainer.lineFragmentPadding = 0;
self.automaticallyAdjustsScrollViewInsets = NO;
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"相册" style:UIBarButtonItemStylePlain target:self action:@selector(enterPhotoAlbum)];
}
-(void)enterPhotoAlbum{
WS(__weakMe);
[PhotoCatcherManager requestAuthorizationHandler:^(BOOL isAuthorized) {
if (isAuthorized) {
PhotoController * vc = [PhotoController new];
vc.photoCallBackBlock = ^(NSArray * photos){
[__weakMe setTextViewWithPhotos:photos];
};
[__weakMe.navigationController pushViewController:vc animated:YES];
}else{
UIAlertController * vc = [UIAlertController alertControllerWithTitle:@"您没赋予本程序相机权限" message:@"您可以在iOS系统的“设置→隐私→相机”中赋予本程序相机权限" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction * action = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
}];
[vc addAction:action];
[__weakMe presentViewController:vc animated:NO completion:NULL];
return ;
}
}];
}
-(void)setTextViewWithPhotos:(NSArray*)photos{
for (NSDictionary * dic in photos) {
UIImage * image = dic[EEPhotoImage];
NSUInteger location = self.textView.selectedRange.location ;
NSTextAttachment * attachMent = [[NSTextAttachment alloc] init];
attachMent.image = image;
CGSize size = [self displaySizeWithImage:image];
attachMent.bounds = CGRectMake(0, 0, size.width,size.height);
NSAttributedString * attStr = [NSAttributedString attributedStringWithAttachment:attachMent];
NSMutableAttributedString *textViewString = [self.textView.attributedText mutableCopy];
[textViewString insertAttributedString:attStr atIndex:location];
[textViewString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:19] range:NSMakeRange(0, textViewString.length)];
self.textView.attributedText = textViewString;
self.textView.selectedRange = NSMakeRange(location + 1,0);
}
}
//显示图片的大小 （全屏）
- (CGSize)displaySizeWithImage:(UIImage *)image {
CGSize displaySize;
if (image.size.width !=0 ) {
CGFloat _widthRadio = APPCONFIG_UI_SCREEN_FWIDTH / image.size.width;
CGFloat _imageHeight = image.size.height * _widthRadio;
displaySize = CGSizeMake(APPCONFIG_UI_SCREEN_FWIDTH, _imageHeight);
}else{
displaySize = CGSizeZero;
}
return displaySize;
}
2.2. ViewControllerB.h ( PhotoController )
@interface PhotoController : UIViewController
@property (nonatomic,copy) void(^(photoCallBackBlock))(NSArray *);
@end
2.3.ViewControllerB.m 部分代码( PhotoController )
- (void)viewDidLoad {
self.manager = [PhotoCatcherManager sharedInstance];
self.allPhotos = [PhotoCatcherManager getFetchResultWithMediaType:PHAssetMediaTypeImage ascend:NO];
}
#pragma mark- UICollectionViewDataSource
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
return _allPhotos.count;
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
PhotoCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cell" forIndexPath:indexPath];
cell.selectedBtn.selected = NO;
for (NSIndexPath * index in _selectedArray) {
if (index.row == indexPath.row) {
cell.selectedBtn.selected = YES;
}
}
PHAsset *asset = self.allPhotos[indexPath.item];
WS(weakSelf);
[cell setBtnClickBlock:^(UIButton * btn) {
if (btn.selected) {
if (weakSelf.selectedArray.count>=20) {
MBProgressHUD * hud = [MBProgressHUD showHUDAddedTo:[UIApplication sharedApplication].keyWindow animated:YES];
hud.mode = MBProgressHUDModeText;
hud.label.text = @"本次最多选择20张照片";
[hud hideAnimated:YES afterDelay:2];
btn.selected = NO;
return ;
}
[weakSelf.selectedArray addObject:indexPath];
}else{
[weakSelf.selectedArray removeObject:indexPath];
}
}];
#pragma mark 单张缩略图
[_manager getImageLowQualityForAsset:asset targetSize:ImageSize resultHandler:^(UIImage *result, NSDictionary *info) {
if (result) {
cell.image = result;
}
}];
return cell;
}
#pragma mark- 单张图片
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
PHAsset *asset = self.allPhotos[indexPath.item];
WS(weakSelf);
[_manager getImageHighQualityForAsset:asset progressHandler:^(double progress, NSError *error, BOOL *stop, NSDictionary *info) {
if (error) {
NSLog(@"iClound error: %@ ",error);
return ;
}
_hud.hidden = NO;
_hud.progress = progress;
_hud.label.text = @"同步iCloud中";
NSLog(@"downloading the image from iCloud, progress:~~ %f ~~%@",progress,info);
} resultHandler:^(UIImage *result, NSDictionary *info) {
BOOL downloadFinined = ![[info objectForKey:PHImageResultIsDegradedKey] boolValue];
if (downloadFinined) {
[weakSelf.hud setHidden:YES];
}
weakSelf.browserView.image = result;
weakSelf.browserView.hidden = NO;
}];
}
#pragma mark- 选取多张图片
-(void)finishSelected{
NSMutableArray * assets = [NSMutableArray array];
WS(weakSelf);
for (NSIndexPath * indexPath in _selectedArray) {
PHAsset * asset = self.allPhotos[indexPath.item];
[assets addObject:asset];
}
[_manager getImagesForAssets:assets progressHandler:^(double progress, NSError *error, BOOL *stop, NSDictionary *info) {
if (error) {
NSLog(@"iClound error: %@ ",error);
return ;
}
weakSelf.hud.hidden = NO;
weakSelf.hud.progress = progress;
weakSelf.hud.label.text = @"同步iCloud中";
NSLog(@"downloading the image from iCloud, progress:~~ %f ~~%@",progress,info);
} resultHandler:^(NSArray<NSDictionary *> *result) {
weakSelf.hud.hidden = YES;
[weakSelf.navigationController popViewControllerAnimated:YES];
weakSelf.photoCallBackBlock(result);
}];
}
