Apple’s documentation is notorious in a way that it doesn’t explain how to do something sometimes. Sometimes, explanation misleads how to do things, and sometimes it doesn’t explain about what you want to do at all.
Drag & Drop programming with Cocoa is such a case. So, it would be better if there is a way to figure out what is going on.
I found one, which is called Drag Peeker X.
How to use is very simple. Just drag and drop things on the Drag Peeker X’s window. Then it will reveal what information the drag source, in other words, the program the drag was initiated, exports.
Especially, when you want to confirm what a Carbon application is written to accept by checking its counterpart Drag source program exports, this kind of debugging is quite useful.
For example, I wrote some code to enable users to drag an item from my program to the Final Cut Pro’s project window. Although the FCP accept drag&drop from the Finder, but it doesn’t work with my program. So, I wanted to know what information the Finder exports and the FCP accepts. I think the Apple Inc. itself should provide this kind of utility program.
I will write more about Drag&Drop programming from now on.