ios 避免输入框被键盘遮挡

使用库：IQKeyboardManager

方法：

1，pod引入：
pod 'IQKeyboardManager'

2，控制自动键盘功能启用与否：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    //默认为YES，关闭为NO
    [IQKeyboardManager sharedManager].enable = YES;
}