将 UIImage 转换为字节

Question

I am getting UIImage using UIImagePickerController. How can i calculate number of bytes hold by that Image in kb/mb?

Using that values I have to make logic that user cant add Images more than size of 1MB

Answer 1

Sure you can. Convert the UIImage to a NSData object, which has the length property, which will give you its size in bytes. Then you can easily calculate the size in whatever unit you need.

So for example:

    UIImage *img = [UIImage imageNamed:@"some.png"];
    NSData *dataObj = UIImageJPEGRepresentation(img, 1.0);
    int bytes = [dataObj length];
    //convert into whatever unit you need

Answer 2

You can get image size from following delegate method of UIImagePickerController

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo{
     if([UIImageJPEGRepresentation(image, 1.0) length]> MAX_SIZE)
     {
         //Code here
     }
}

Here, You can see, I have converted Image into data, and [data length] can give bytes length.

Answer 3

Rather than stopping the user from uploading images of more than 1MB, you would serve your user better by scaling and compressing the image to save space I suspect. However to answer your question, one way would simply be;

-(void)imagePickerController:(UIImagePickerController *) picker didFinishPickingMediaWithInfo:(NSDictionary *) info {


NSData *imageData = UIImagePNGRepresentation(image); // Or UIImageJPEGRepresentation 
long sizeInBytes = [imageData length];

// do stuff

}