在UIImageView中获取图像的大小

Question

I am having trouble getting the size of an image after it has been assigned to an UIImageView programmatically.

The code below runs in a loop and a function is used (getNoteImage) to download an image from an URL (photoURL) and assign it to the created UIImageView. I need to get the height of the image so that I can calculate the spacing for the following images and labels.

        var myImage :UIImageView

        myImage = UIImageView(frame: CGRectMake(0, 0, UIScreen.mainScreen().bounds.width, UIScreen.mainScreen().bounds.height))

        myImage.center = CGPointMake(UIScreen.mainScreen().bounds.size.width/2, imageY)

        myImage.getNoteImage(photoUrl)

        self.detailsView.addSubview(myImage)

        myImage.contentMode = UIViewContentMode.ScaleAspectFit

        imageHeight = myImage.bounds.size.height

I have tried using

imageHeight = myImage.bounds.size.height

which I read as a solution on another post but his just returns the screen size for the device (667 on the iPhone6 simulator).

Can anyone guide me on how I can get the correct image size ? Thanks

Answer 1

As your imageView is taking up the whole screen and the image is sized using 'aspect fit' to get the height the image is displayed at you will need to get the original image size using myImage.image!.size then scale this based on myImage.bounds.size something like;

let imageViewHeight = myImage.bounds.height
let imageViewWidth = myImage.bounds.width
let imageSize = myImage.image!.size
let scaledImageHeight = min(imageSize.height * (imageViewWidth / imageSize.width), imageViewHeight)

That should give the actual height of the image, note that image.size gives the "logical dimensions of the image" ie its natural size and not the size it is drawn at.

Answer 2

As UIImage official doc :

if let image = myImage.image {
       let size = image.size
       print("image size is \(size)")
} else { 
    print("There is no image here..")
}

I suppose your code working with synchronously image as I understand in your question, but if not I recommended to use AlamofireImage .

With AlamofireImage you can do:

self.myImage.af_setImageWithURL(
    NSURL(string: photoUrl)!,
    placeholderImage: nil,
    filter: nil,
    imageTransition: .CrossDissolve(0.5),
    completion: { response in
        print(response.result.value) # UIImage  
        if let image = response.result.value {
           let size = image.size
           print("image size is \(size)")
        }
        print(response.result.error) # NSError
    }
)

Answer 3

change your code like this and try again. only you did note force set the frame of the UIImageView and then give it a image ,you can use "imageHeight = myImage.bounds.size.height" get the real size of the image.

    var myImage :UIImageView
    //remove your initial frame parameters
    myImage = UIImageView()
    myImage.center = CGPointMake(UIScreen.mainScreen().bounds.size.width/2, imageY)

Answer 4

try using myImage.image.size.height and also make sure the image is downloaded from the url you should write it in a completion block and only check if the image is downloaded. See the documentation for more details.