Plain textfield text gets cut off after clicking on return key on iOS simulator

Question

One weird thing happens with my code. Everything goes well till i am typing text in the textfield but as soon as I click return key my textfield text gets cut off from bottom. For more information i have attached some screenshots of my iPhone simulator. Here is my screen

Then Once i start editing my textfield simulator pops up keypad

but as soon as i clicked on return key which is present in the keypad my text gets cut off from bottom

Anybody can help me out? Thanks in advance :)