Use of Touch ID (Fingerprint Identification Technology) in iOS

Apple opened up fingerprint recognition technology after iOS8, and encapsulated it into the LocalAuthentication framework, which means that third-party apps are allowed to authenticate through touch ID, and the method of use is extremely simple.

touch ID usage process

1 Import the LocalAuthentication/LocalAuthentication.h framework
2 Make various conditional judgments, and start using if the conditions are met

    // 判断设备是否支持touchId
    if ([[UIDevice currentDevice].systemVersion floatValue] < 8.0) {
        NSLog(@"系统版本太低，无法进行指纹识别");
        return;
    }

    // 创建验证对象的上下文
    LAContext *context = [[LAContext alloc]init];

    // 判断设备是否允许使用生物识别技术
    if (![context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:nil]) {
         NSLog(@"指纹识别技术暂不可用");
        return;
    }

    // 如果条件都满足则开始使用指纹识别
    // localizedReason 传入使用指纹识别的原因
    [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:@"验证指纹，以便打开程序" reply:^(BOOL success, NSError * _Nullable error) {

        // 指纹识别成功
        if (success) {
            NSLog(@"指纹识别成功");
        }

        // 指纹识别失败
        switch (error.code){
            case LAErrorSystemCancel:
                // 可能是您将程序切换出去了，所以系统取消了验证
                NSLog(@"系统取消了验证");
                break;
            case LAErrorUserCancel:
                NSLog(@"用户取消了验证");
                break;
            case LAErrorUserFallback:
                // 用户选择输入密码，切换到主线程进行后续处理
                NSLog(@"用户选择输入密码");
                break;
        }
    }];

The following figure is an example of the pop-up fingerprint recognition pop-up window

. The first touchID is the name of the app, and the "verify fingerprint to open the program" below is the incoming use reason.