changed default placeholder color to 0.7

Placeholder text was dark compared to UITextField placeholder so changed the default value to [UIColor colorWithWhite:0.7 alpha:0.7f] 
Ref:
http://stackoverflow.com/questions/21074417/change-of-uitextfield-placeholder-color
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITextField_Class/#//apple_ref/occ/instp/UITextField/attributedPlaceholder