This problem has been occuring for about 1 to 2 weeks
iPhone 6, iOS 8.3
Get the screen fixed.
The solution is an easy one. As Templeton Peck suggests, get the screen fixed at an Apple store. Make an appointment at an Apple Store to have your device examined by a technician. Or contact Apple Support. Be sure to back up your device before taking or sending it to Apple.
I have a cracked iphone 6 screen in a line and whenever i try to delete more than 1 or 2 messages it wont let me delete it i would have to go out and back in the app or wait a couple of mins
