如何从Ios上传相册中的图像

问题描述

我想上传通过相机捕获的图片。

I want to upload image which is capturing by camera .

推荐答案

`UIImagePickerControllerReferenceURL` will return reference to local storage of your selected image.

    NSURL* localUrl = (NSURL *)[info valueForKey:UIImagePickerControllerReferenceURL];

Now you can save this url in your database.

To retrieve the image : 

The API has changed the rules slightly and you dont get direct file system access to the iPhoto library any more. Instead you get asset library URL's like this. 

`assets-library://asset/asset.JPG?id=1000000003&ext=JPG`

You use the ALAssetLibrary object to access the ALAsset object via the URL.

so from the docs for ALAssetLibrary throw this in a header (or your source)

    typedef void (^ALAssetsLibraryAssetForURLResultBlock)(ALAsset *asset);
    typedef void (^ALAssetsLibraryAccessFailureBlock)(NSError *error);

which isnt strictly needed but keeps things pretty.  
and then in your source.

    -(void)findLargeImage
    {
    	NSString *mediaurl = [self.node valueForKey:kVMMediaURL];
    
    	//
    	ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
    	{
    		ALAssetRepresentation *rep = [myasset defaultRepresentation];
    		CGImageRef iref = [rep fullResolutionImage];
    		if (iref) {
    			largeimage = [UIImage imageWithCGImage:iref];
    			[largeimage retain];
    		}
    	};
    	
    	//
    	ALAssetsLibraryAccessFailureBlock failureblock  = ^(NSError *myerror)
    	{
    		NSLog(@"booya, cant get image - %@",[myerror localizedDescription]);
    	};
    		
    	if(mediaurl && [mediaurl length] && ![[mediaurl pathExtension] isEqualToString:AUDIO_EXTENSION])
    	{
    		[largeimage release];
    		NSURL *asseturl = [NSURL URLWithString:mediaurl];
    		ALAssetsLibrary* assetslibrary = [[[ALAssetsLibrary alloc] init] autorelease];
    		[assetslibrary assetForURL:asseturl 
    					   resultBlock:resultblock
    					  failureBlock:failureblock];
    	}
    }



A couple of things to note are that this uses blocks which were new to me before I started my iOS4 porting but you might like to look at 

http://www.mikeash.com/pyblog/friday-qa-2008-12-26.html

and 

http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/Blocks/Articles/00_Introduction.html

They bend your head a little but if you think of them as notification selectors or callbacks it kind of helps.

Also 

 - when `findLargeImage` returns the
   resultblock wont have run yet as its
   a callback. So largeImage wont be
   valid yet. 
 - `largeImage` needs to be an
   instance variable not scoped to the
   method.

I use this construct to do this when using the method but you may find something more suitable to your use.

    [node.view findLargeImage];
    UIImage *thumb = node.view.largeImage;
    if (thumb) { blah blah }

Thats what I learned while trying to get this working anyway.

**iOS 5 update**

When the result block fires seems to be a bit slower with iOS5 & maybe single core devices so I couldnt rely on the image to be available directly after calling `findLargeImage`. So I changed it to call out to a delegate.

    @protocol HiresImageDelegate <nsobject>
    @optional
    -(void)hiresImageAvailable:(UIImage *)aimage;
    @end

and comme cá

    //
        ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
        {
            ALAssetRepresentation *rep = [myasset defaultRepresentation];
            CGImageRef iref = [rep fullResolutionImage];
            if (iref) {
                UIImage *largeimage = [UIImage imageWithCGImage:iref];
                [delegate hiresImageAvailable:large];
            }
        };</nsobject>

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