简单实现app使用PC图片

提一个很人性化的需求:

 

在自己的app里使用PC里的图片。

关键点:传输。怎么把图片从PC导入自己的APP。

因为iOS的封闭性,一般用户不能很方便把图片导入手机相册。笔者稍微想了下,实现功能其实也有不少办法。

就一般用户而言,可以通过第三方app中转一下,比如某Q,传到手机,再保存到相册,再从相册中导入。

针对开发自己的app,也有通过上传到服务器中转,ftp直连等等。都可以实现,从中,笔者选择自以为最简单的方式进行了实现。

流程大概如下:

1、通过iTunes将图片上传到app的document里

2、遍历document文件,将图片保存至相册后清除沙盒图片

3、使用系统UIImagePickerController读取图片。

解释一下,虽然可以直接读取document图片,但是那样得自己画界面,麻烦。加载到系统相册,然后甚至可以专门自定义一个图片目录。一目了然,而且对于用户来说,使用自己添加的图片和使用系统相册图片一样,没有学习成本。


主要步骤:

1、通过iTunes将图片上传到app的document里:

要让自己的app可以使用iTunes添加图片,需要在-info.plist里添加配置

Application supports iTunes file sharing -> YES

然后打开iTunes,找到设备,在应用程序的文件共享里可以找到自己的app,右下角添加图片。

 

2、遍历document文件,将图片保存至相册后清除沙盒图片

iTunes里添加的文件的路径其实就是放在app沙盒的document目录。明确了这一点。我们就可以把文件便利出来了。

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NSString *filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
     
NSFileManager *fileManager = [NSFileManager defaultManager];
//注意:
//这个会遍历出文件夹的子目录
NSDirectoryEnumerator *dirEnum = [fileManager enumeratorAtPath:filePath];
//这个只会在根目录遍历文件
 NSArray *dirContents = [fileManager contentsOfDirectoryAtPath:filePath error:nil];

把图片保存到相册的方法是

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void UIImageWriteToSavedPhotosAlbum (
   UIImage  *image,
   id       completionTarget,
   SEL      completionSelector,
   void     *contextInfo
);

你可以直接

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UIImageWriteToSavedPhotosAlbum(img, nil, nil, nil);

一般来说没问题,但图片多了可能会出现丢失的现象,所以我借鉴大家的做法做一个优化

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-(void) saveNext{
    if (listOfImages.count > 0) {
        UIImage *image = [listOfImages objectAtIndex:0];
        UIImageWriteToSavedPhotosAlbum(image, self, @selector(savedPhotoImage:didFinishSavingWithError:contextInfo:), nil);
    }
    else {
        [self allDone];
    }
}
 
-(void) savedPhotoImage:(UIImage*)image didFinishSavingWithError: (NSError *)error contextInfo: (void *)contextInfo {
    if (error) {
        //NSLog(@"%@", error.localizedDescription);
    }
    else {
        [listOfImages removeObjectAtIndex:0];
    }
    [self saveNext];
}

优化的原理是进行了一个递归,确保一次完成再进行下一次。

这样,document下的图片便都保存至了系统的相册。但是我觉得还不够,我希望能够将自己从iTunes里添加的图片,专门放在一个目录下,方便查阅。于是,就上面的方法,我再次进行了一点改造。

这一次,我们使用到了AssetsLibrary。

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-(void)saveImage:(UIImage*)image toAlbum:(NSString*)albumName withCompletionBlock:(SaveImageCompletion)completionBlock
{
    //write the image data to the assets library (camera roll)
    [self writeImageToSavedPhotosAlbum:image.CGImage orientation:(ALAssetOrientation)image.imageOrientation
                        completionBlock:^(NSURL* assetURL, NSError* error) {
                          //error handling
                          if (error!=nil) {
                              completionBlock(error);
                              return;
                          }
                          //add the asset to the custom photo album
                          [self addAssetURL: assetURL
                                    toAlbum:albumName
                        withCompletionBlock:completionBlock];
                      }];
}
 
-(void)addAssetURL:(NSURL*)assetURL toAlbum:(NSString*)albumName withCompletionBlock:(SaveImageCompletion)completionBlock
{
    __block BOOL albumWasFound = NO;
    //search all photo albums in the library
    [self enumerateGroupsWithTypes:ALAssetsGroupAlbum
                        usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
                            //compare the names of the albums
                            if ([albumName compare: [group valueForProperty:ALAssetsGroupPropertyName]]==NSOrderedSame) {
                                //target album is found
                                albumWasFound = YES;
                                //get a hold of the photo‘s asset instance
                                [self assetForURL: assetURL
                                      resultBlock:^(ALAsset *asset) {
                                          //add photo to the target album
                                          [group addAsset: asset];
                                          //run the completion block
                                          completionBlock(nil);
                                      } failureBlock: completionBlock];
                                //album was found, bail out of the method
                                return;
                            }
                            if (group==nil && albumWasFound==NO) {
                                //photo albums are over, target album does not exist, thus create it
                                __weak ALAssetsLibrary* weakSelf = self;
                                //create new assets album
                                [self addAssetsGroupAlbumWithName:albumName
                                                      resultBlock:^(ALAssetsGroup *group) {
                                                          //get the photo‘s instance
                                                          [weakSelf assetForURL: assetURL
                                                                        resultBlock:^(ALAsset *asset) {
                                                                            //add photo to the newly created album
                                                                            [group addAsset: asset];
                                                                            //call the completion block
                                                                            completionBlock(nil);
                                                                        } failureBlock: completionBlock];
                                                      } failureBlock: completionBlock];
                                //should be the last iteration anyway, but just in case
                                return;
                            }
                        } failureBlock: completionBlock];
}

AssetsLibrary笔者写文时了解不深,能实现功能,其他不深入讨论。

使用:

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[self.library saveImage:image toAlbum:@"File Share" withCompletionBlock:^(NSError *error) {
            if (error!=nil) {
                NSLog(@"Big error: %@", [error description]);
            }
            [listOfImages removeObjectAtIndex:0];
            [self saveNext];
        }];

3、使用系统UIImagePickerController读取图片。这个也不多说,固定套路。

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- (void)getImagePicker:(NSUInteger)sourceType {
 
    UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
     
    imagePickerController.delegate = self;
     
    imagePickerController.allowsEditing = YES;
     
    imagePickerController.sourceType = sourceType;
     
    [self presentViewController:imagePickerController animated:YES completion:^{}];
}
 
#pragma mark - image picker delegte
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    [picker dismissViewControllerAnimated:YES completion:^{}];
     
    NSLog(@"did");
}
 
- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
    [self dismissViewControllerAnimated:YES completion:^{}];
    NSLog(@"didn‘t");
}

使用

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[self getImagePicker:UIImagePickerControllerSourceTypePhotoLibrary];

最终效果


 

PS:其实真是简单实现,写了很多其实是自己的分析过程。实现功能几十行代码就能搞定。

另外,之所以iTunes里上传了四张图片而最终只有三张,不是图片丢失,而是我判断图片文件的时候通过后缀,并且抛弃了gif。也不知道有没有更好的方法。

我想过直接把遍历的所有文件全部转成Image,然后通过!(image)来判断。但感觉会很费内存。恕笔者无知。欢迎大神斧正。

 

附上demo。 http://pan.baidu.com/s/1hqHXBE0 真尴尬,CSDN上传不上去,大家凑合这用吧

简单实现app使用PC图片,,5-wow.com

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