iOS中自定义相册(上)

作者: 傲视苍穹 | 来源:发表于2016-10-31 20:26 被阅读144次

第一首先创建一个管理相片的单列类 (必须导入相册对应的类库 @import AssetsLibrary; @import UIKit;

从ALAsset对象中获取UIImage对象 [UIImage imageWithCGImage:asset.aspectRatioThumbnail]]

  • 需要定义必要的一些属性和回调Block。
//回调Block
typedef void(^ALAssetGroupBlock)(NSArray <ALAssetsGroup *> * groups);
typedef void(^ALAssetPhotoBlock)(NSArray <ALAsset *> * photos);
typedef void(^ALAssetFailBlock)(NSString * error);

//属性
@property (nonatomic, strong) ALAssetsLibrary * library;//相册库
@property (nonatomic, copy) ALAssetGroupBlock block;
@property (nonatomic, strong) NSMutableArray <ALAssetsGroup *> * groups;//存放所有照片组的数组对象
@property (nonatomic, strong) NSMutableArray <ALAsset *> * photos;//存放所有照片的数组对象

  • 创建单列类和初始化属性。
-(instancetype)init
{
    if (self = [super init])
    {
        //实例化库对象
        self.library = [[ALAssetsLibrary alloc]init];
        //初始化数组
        self.groups = [NSMutableArray arrayWithCapacity:0];
        self.photos = [NSMutableArray arrayWithCapacity:0];
    }
    return self;
}


+(instancetype)shareInstance
{
    static RTPhotoManager * photoManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        photoManager = [[RTPhotoManager alloc]init];
    });
    return photoManager;
}

  • 创建组名叫做title的相片组
- (void)createGroupWithTitle:(NSString *)title
{
    //开始创建
    [self.library addAssetsGroupAlbumWithName:title resultBlock:^(ALAssetsGroup *group) {
        NSLog(@"创建成功!");
    } failureBlock:^(NSError *error) {
        NSLog(@"error = %@",error.localizedDescription);
    }];
}

  • 判断是否包含相机胶卷
- (BOOL)containCameraRoll:(ALAssetsGroup *)group
{
    //如果是相机胶卷,放到第一位,这里只适配英文以及中文
    NSString * nameCN = NSLocalizedString([group valueForProperty:ALAssetsGroupPropertyName], @"");
    NSString * nameEN = NSLocalizedString([group valueForProperty:ALAssetsGroupPropertyName], @"");
    //对当前组数进行排序
    if ([nameCN isEqualToString:@"相机胶卷"]
        || [nameEN isEqualToString:@"Camera Roll"])
    {
        //修改变量
        return YES;
    }
    return NO;
}

  • 读取相册的所有组
-(void)readAllPhotoGroups:(ALAssetGroupBlock)groupBlock Fail:(ALAssetFailBlock)failBlock CameraRollHandel:(void (^)(void))cameraRollHandle
{
    //删除之前存的所有组
    [self.groups removeAllObjects];
    __block __weak typeof(self) copy_self = self;
    //开始遍历
    [self.library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
        //如果返回的组存在
        if (group)
        {
            //对group进行过滤,只要照片
            [group setAssetsFilter:[ALAssetsFilter allPhotos]];
            //添加数据
            [copy_self.groups addObject:group];
            //进行顺序判断
            if([self containCameraRoll:group] == true)
            {
                //删除当前位置的数组
                [self.groups removeObjectAtIndex:self.groups.count - 1];
                [self.groups insertObject:group atIndex:0];
            }
            //回调数据
            groupBlock([NSArray arrayWithArray:copy_self.groups]);
            //进行序列后的回调
            if([self containCameraRoll:group] == true)
                cameraRollHandle();     
        }
    } failureBlock:^(NSError *error) { 
        //失败回调
        failBlock(error.localizedDescription);
    }];
}

  • 打开相片组
-(void)openPhotosGroup:(ALAssetsGroup *)assetsGroup Success:(ALAssetPhotoBlock)successBlock Fail:(ALAssetFailBlock)failBlock
{
    //删除所有的照片对象
    [self.photos removeAllObjects];
    //避免强引用
    __block __weak typeof(self) copy_self = self;
    //获取当前组的url数据
    NSURL * url = [assetsGroup valueForProperty:ALAssetsGroupPropertyURL]; 
    //打开向前的组
    [self.library groupForURL:url resultBlock:^(ALAssetsGroup *group) {
        [copy_self photosInGroups:group Block:successBlock];
    } failureBlock:^(NSError *error) {
        //失败的回调
        failBlock(error.localizedDescription);
    }];
}
  • 获取所有的照片对象
- (void)photosInGroups:(ALAssetsGroup *)group Block:(ALAssetPhotoBlock)photoBlock
{
    //开始读取
    [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {
        //如果不为空或者媒体为图片
        if (result != nil && [[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto])
        {    
            //添加数据
            [self.photos addObject:result];
            //数目达标后统一进行回调
            if (index == group.numberOfAssets - 1)
            {
                //回调
                photoBlock([NSArray arrayWithArray:self.photos]);    
            }
        }
    }];
}

第二就用 UICollectionView 展示相册中的图片

  • 首先获得相册管理的单列对象。
    self.photoManager = [RTPhotoManager shareInstance];
  • 从单列对象里取出相册中所有的图片组。
- (void)requestPhotoGroup
{
    //避免强引用
    __block __weak typeof(self) copy_self = self;
    //开始请求
    [self.photoManager readAllPhotoGroups:^(NSArray<ALAssetsGroup *> *groups) {
        copy_self.groupArray = groups;
    
    } Fail:^(NSString *error) {} CameraRollHandel:^{
        
          [self loadPhotosWithGroup:self.groupArray.firstObject];
    self.navigationItem.title = [self.groupArray.firstObject valueForProperty:ALAssetsGroupPropertyName];
        
    }];
}
  • 然后从每个图片组中取出对于的图片。

- (void)loadPhotosWithGroup:(ALAssetsGroup *)assetsGroup
{
    
    [self.photoManager openPhotosGroup:assetsGroup Success:^(NSArray<ALAsset *> *photos) {
        self.photos = [NSMutableArray arrayWithArray:photos];
        //刷新
        [self.collectionView reloadData];
        //滚动到最后一个的位置
        [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:self.photos.count - 1 inSection:0] atScrollPosition:UICollectionViewScrollPositionBottom animated:false];
        
    } Fail:^(NSString *error) {
        
        NSLog(@"error = %@",error);
        
    }];
}
  • 最后就是把每组的图片展示在UICollectionView上。

注:是由中心点取正方形范围的图片(可以用于展示的缩略图;而用ALAsset 对象取得thumbnail 缩略图比较模糊)

- (UIImage*)getThumbnailImage:(UIImage *)image {
    float imgwidth = image.size.width;
    float imgheight = image.size.height;
    float viewwidth = 0;
    float viewheight = 0;
    if (MAX(imgwidth, imgheight) == imgheight) {
        viewwidth = imgwidth;
        viewheight = imgwidth;
    }else{
        viewwidth = imgheight;
        viewheight = imgheight;
    }
    CGRect rect = CGRectMake((imgwidth-viewwidth)/2, (imgheight-viewheight)/2, viewwidth, viewheight);
    CGImageRef subImageRef = CGImageCreateWithImageInRect(image.CGImage, rect);
    CGRect smallBounds = CGRectMake(0, 0, CGImageGetWidth(subImageRef), CGImageGetHeight(subImageRef));
    UIGraphicsBeginImageContext(smallBounds.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextDrawImage(context, smallBounds, subImageRef);
    UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];
    UIGraphicsEndImageContext();
    return smallImage;

}

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网友评论

  • 心语风尚:ios11 拿到所有图片对象 展示在列表中 滚动会卡顿 是因为 request强求图片block 貌似有自带的缓存api但是 没有效果 可能我用的不对
  • GavinKang:大神,ALAsset这一种不兼容 iOS10.0吧??4.0-9.0

本文标题:iOS中自定义相册(上)

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