If your app is mobile app , then definitelly I would search for investor. Investor for mobile app could be:
1. Business angel
2. Some mobile app company which may be interested in your app, but mostly they want finished product from my experience.
I have done 3 mobile apps, and definitelly you cannot succeed unless you have large funds for marketing or extreme luck to be reviewed on some major sites. The key is to go viral and basically everyone knows it, so its not easy without money. Just to give you idea how strong competition on mobile apps is, one smaller mobile company (considering what companies are on market) invests 150 000 USD per month for marketing only. So, when you release app, you need large amount of installs and that costs.
Now, if you partner with some mobile app company, you can share revenues with them. Note: they can advertise your app from their apps. However, its not easy to find such company, I think best is personal meeting or telephone contact.
Another approach is to find a partner, a developer who would continue developing your app. Then you would need to share revenues with him also. Certainly, it has to be some experienced coder with few years of experience. So, if you have funds, continue on your own, but dont spend fortune on app, don't make yourself broke after completing app. Some apps can be developed for 3 - 4000$ so its not that costly considering future potential earnings. Chances that you will succeed even if you have great app are small, you will need huge marketing budget or some excellent mobile company who can push your app through their apps (though it does not guarantee anything at all).
However, if you have developed desktop app, in your case I would continue self funding and start selling on my own. You could approach few companies as well after you finish product.
Many try to develop apps and many do, but very few succeed. My advise is that even if someone offer you 50-50% profit sharing its a good deal. 50% of something is better than 100% of nothing.
Good luck in your sales.