iphonecocoacocoa-touchuikitcore-graphics

Get size of image without loading in to memory


I have several .png images (ETA: but the format could also be JPEG or something else) that I am going to display in UITableViewCells. Right now, in order to get the row heights, I load in the images, get their size properties, and use that to figure out how high to make the rows (calculating any necessary changes along the way, since most of the images get resized before being displayed). In order to speed things up and reduce memory usage, I'd like to be able to get size without loading the images. Is there a way to do this?

Note: I know that there are a number of shortcuts I could implement to eliminate this issue, but for several reasons I can't resize images in advance or collect the image sizes in advance, forcing me to get this info at run time.


Solution

  • As of iOS SDK 4.0, this task can be accomplished with the ImageIO framework (CGImageSource...). I have answered a similar question here.