- (void)beginAuthentication{

    LAContext *context = [[LAContext alloc] init];

    NSError *eror = nil;

    NSString *reson = @"指纹识别";

    if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&eror]) {//支持指纹识别

        [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:reson reply:^(BOOL success, NSError * _Nullable error) {

            if (success) {//指纹验证成功

                NSLog(@"识别成功");

            }else{

                //具体erro.code的错误描述在LAError.h的头文件里

                switch (error.code ) {

                    case LAErrorUserFallback://用户选择输入密码

                        NSLog(@"输入密码");

                        break;

                    case LAErrorTouchIDLockout://用户多次验证失败

                        NSLog(@"多次错误");

                    default:

                        NSLog(@"errorcode == %@",error );

                        break;

                }

            }

        }];

    }else{//不支持指纹识别

        NSLog(@"%@",eror);

    }

}