Quick fixes to make this a tad nicer/safer.

Your category name (and filename, but that I can influence by placing your file in a subfolder) is unsafe. If I add another framework that uses similar utility code, I may get a collision and not even notice it. So I've prefixed the category name. Ideally, the files would be named "NSTimer+JDBlocks.*" as well, but I presume that'd break stuff for you at this point.

I also moved the timer into a dictionary. Not strictly necessary, but provides for less surprise (all other classes restrict userInfo to dictionaries). And finally, found a trailing ';' in an implementation that I cleaned up.

All these edits were done on Github, so I hope this still compiles.