I want to know is there any default size for Navigationbar icons.where designer need to design it.Should they design it for retina and non-retina display.At present I'm using images downloaded from internet which are not looking great.
Create navigation bar icon in the following sizes:
About 44 x 44 pixels
About 22 x 22 pixels (standard resolution)
more informtation you can find here https://developer.apple.com/library/ios/documentation/userexperience/conceptual/mobilehig/BarIcons.html