键盘类型

键盘种类UIKeyboardType枚举：

    UIKeyboardTypeDefault,                // 默认键盘：支持所有字符   
    UIKeyboardTypeASCIICapable,           // 支持ASCII的默认键盘   
    UIKeyboardTypeNumbersAndPunctuation,  // 标准电话键盘，支持+*#等符号   
    UIKeyboardTypeURL,                    // URL键盘，有.com按钮；只支持URL字符   
    UIKeyboardTypeNumberPad,              //数字键盘   
    UIKeyboardTypePhonePad,               // 电话键盘   
    UIKeyboardTypeNamePhonePad,           // 电话键盘，也支持输入人名字   
    UIKeyboardTypeEmailAddress,           // 用于输入电子邮件地址的键盘   
} UIKeyboardType;  

键盘外观UIKeyboardAppearance枚举：

typedef enum {  
    UIKeyboardAppearanceDefault,    // 默认外观：浅灰色   
    UIKeyboardAppearanceAlert,      //深灰/石墨色   
} UIKeyboardAppearance;