After trying to setup the WordPress iPhone app and running into “incorrect username or password” errors, I finally sorted it out. It looks like there are quite a few other people with the same problem so I thought I would post it up. For the record I have a self-host setup.
Firstly – go online on your computer (not your iPhone!) and make sure in your wordpress dashboard you have XML-RPC turned on. It’s located in Settings>Writing>Remote Publishing. Turn it off and on again if its already on (I tried that and it seemed to work!)
Then back on your iPhone – try entering your username and password again. You might as I experienced then get past the login screen but now be met with a “Communication Error – Bad user name or password” error! No fear – patience is needed here!
Now try deleting the blank blog that has been created by clicking on the top right edit button. Then restart the app and try entering all your login details again. It should now work. (fingers crossed)
No guarantees as it worked for me after a few attempts but that’s not to say it will for you!