iOS系统提供的默认键盘类型有12种
UIKeyboardTypeDefault
UIKeyboardTypeASCIICapable
UIKeyboardTypeNumbersAndPunctuation
UIKeyboardTypeURL
UIKeyboardTypeNumberPad
UIKeyboardTypePhonePad
UIKeyboardTypeNamePhonePad
UIKeyboardTypeEmailAddress
UIKeyboardTypeDecimalPad
UIKeyboardTypeTwitter
UIKeyboardTypeWebSearch
UIKeyboardTypeAlphabet
android键盘类型