将UIImage转换为NSData

Question

我在我的应用程序中使用此代码,这将帮助我发送图像.

但是,我有一个带图像的图像视图.我没有appbundle文件,但我的身边有图像.如何更改以下代码？任何人都可以告诉我如何转换myimage为NSData？

// Attach an image to the email
NSString *path = [[NSBundle mainBundle] pathForResource:@"rainy" ofType:@"jpg"];
NSData *myData = [NSData dataWithContentsOfFile:path];
[picker addAttachmentData:myData mimeType:@"image/jpeg" fileName:@"rainy"];

Answer 1

请尝试以下操作之一,具体取决于您的图像格式:

UIImageJPEGRepresentation

以JPEG格式返回指定图像的数据.

NSData * UIImageJPEGRepresentation (
   UIImage *image,
   CGFloat compressionQuality
);

UIImagePNGRepresentation

以PNG格式返回指定图像的数据

NSData * UIImagePNGRepresentation (
   UIImage *image
);

这里的文档.

编辑:

如果要访问构成UIImage的原始字节,可以使用以下方法:

CGDataProviderRef provider = CGImageGetDataProvider(image.CGImage);
NSData* data = (id)CFBridgingRelease(CGDataProviderCopyData(provider));
const uint8_t* bytes = [data bytes];

这将为您提供图像RGB像素的低级表示.(CFBridgingRelease如果您不使用ARC,请忽略该位).

Answer 2

NSData *imageData = UIImagePNGRepresentation(myImage.image);

Answer 3

如果你在UIImageView中有一个图像,例如"myImageView",你可以执行以下操作:

使用UIImageJPEGRepresentation()或UIImagePNGRepresentation()转换图像,如下所示:

NSData *data = UIImagePNGRepresentation(myImageView.image);
//or
NSData *data = UIImageJPEGRepresentation(myImageView.image, 0.8);
//The float param (0.8 in this example) is the compression quality 
//expressed as a value from 0.0 to 1.0, where 1.0 represents 
//the least compression (or best quality).

您还可以将此代码放在GCD块中并在另一个线程中执行,在此过程中显示UIActivityIndi​​catorView ...

//*code to show a loading view here*

dispatch_queue_t myQueue = dispatch_queue_create("com.my.queue", DISPATCH_QUEUE_SERIAL);

dispatch_async(myQueue, ^{ 

    NSData *data = UIImagePNGRepresentation(myImageView.image);
    //some code....

    dispatch_async( dispatch_get_main_queue(), ^{
        //*code to hide the loading view here*
    });
});

Answer 4

创建图像的引用....

UIImage *rainyImage = [UIImage imageNamed:@"rainy.jpg"];

在图像视图中显示图像... imagedisplay是imageview的参考:

imagedisplay.image = rainyImage;

NSData通过传递UIImage引用将其转换为浮点值并提供压缩质量:

NSData *imgData = UIImageJPEGRepresentation(rainyImage, 0.9);