From iOS 3.2, application can be called to open specify files, lick .zip . we try to implement an application can open the zip attachment file in iOS, it works. But from iOS 4.0, apple provide a new file preview framework call Quick Look Framework. The default email application will open the preview of the file default. But the quick look framework doesn't provide a method to implement the preview of custom file type. Does anyone knows how to solve this problem? Right now if the file type is not support, the email will open a black preview View.