2014-12-17

iOS封装 - TouchID 指纹验证

前言

TouchID已经出来一段时间了，感觉大家已经不再陌生，它是苹果公司在iOS 7中引入并在iPhone 5s上使用的新特性，基于一个Local Authentication的新框架，允许用户解锁设备和在App Store购物的生物识别技术。
它的强大毋庸置疑，在微信，支付宝等等的App中，我们也在市场的使用它，极大的便利我们生活等，在这篇文章中，我会封装一个TouchID类，方便大家在以后使用。

代码

Local Authentication这个框架的核心类便是LAContext类，我们会实例化一个LAContext类来进行操作。

//初始化上下文对象
  LAContext* context = [[LAContext alloc] init];
  //错误对象
  NSError* error = nil;

如果框架无法验证，它抛出一个错误。有多种原因的设备不能够认证。

LAErrorTouchIDNotAvailable 该设备不具有指纹传感器
LAErrorPasscodeNotSet 没有密码的设备，这意味着触摸ID是禁用上设置
LAErrorTouchIDNotEnrolled 有一种密码设定，但该设备还没有被任何指纹配置

其实也就是说，我们需要先去验证设备是否支持TouchID的功能，在老的机型上，比如4，4s，显然是不具备的。

1	[context canEvaluatePolicy: LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]

我们用上面这句代码验证，失败则会返回刚才的三种信息。

如果成功，我们则会经行下一步的操作，看看验证指纹的成功与失败

[context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
               localizedReason:localizedReason
                         reply:
        ^(BOOL succes, NSError *error) {
            if (succes) {
                //验证成功，返回主线程处理
                NSLog(@"验证成功");
                dispatch_async(dispatch_get_main_queue(), ^{
                    backSucces(succes);
                });
                
            } else {
                NSLog(@"验证失败");
                NSLog(@"%@",error.localizedDescription);
                dispatch_async(dispatch_get_main_queue(), ^{
                    backFailure(error.code);
                });
            }
        }];

其实整个过程并不难，这里我用block返回了LAError枚举，本来我想自己自定义枚举进行返回，如下代码

typedef NS_ENUM(NSInteger, TouchIdValidationResult)
{
    kTouchIdSystemCancel,   // 切换到其他APP
    kTouchIdUserCancel,     // 用户取消验证Touch ID
    kTouchIdUserFallback,   // 用户点击其他按钮
    kTouchIdNotEnrolled,    // 不支持TouchId机型
    kTouchIdPasscodeNotSet, // 没有设置验证密码
    kTouchIdOther           // 其他
};

但我发现，没有什么比自带的LAError枚举更加详细了，同时他也给出了各个枚举的说明含义，如下

typedef NS_ENUM(NSInteger, LAError)
{
    /// Authentication was not successful, because user failed to provide valid credentials.
    LAErrorAuthenticationFailed = kLAErrorAuthenticationFailed,
    
    /// Authentication was canceled by user (e.g. tapped Cancel button).
    LAErrorUserCancel           = kLAErrorUserCancel,
    
    /// Authentication was canceled, because the user tapped the fallback button (Enter Password).
    LAErrorUserFallback         = kLAErrorUserFallback,
    
    /// Authentication was canceled by system (e.g. another application went to foreground).
    LAErrorSystemCancel         = kLAErrorSystemCancel,
    
    /// Authentication could not start, because passcode is not set on the device.
    LAErrorPasscodeNotSet       = kLAErrorPasscodeNotSet,

    /// Authentication could not start, because Touch ID is not available on the device.
    LAErrorTouchIDNotAvailable  = kLAErrorTouchIDNotAvailable,
    
    /// Authentication could not start, because Touch ID has no enrolled fingers.
    LAErrorTouchIDNotEnrolled   = kLAErrorTouchIDNotEnrolled,

    /// Authentication was not successful, because there were too many failed Touch ID attempts and
    /// Touch ID is now locked. Passcode is required to unlock Touch ID, e.g. evaluating
    /// LAPolicyDeviceOwnerAuthenticationWithBiometrics will ask for passcode as a prerequisite.
    LAErrorTouchIDLockout   NS_ENUM_AVAILABLE(10_11, 9_0) = kLAErrorTouchIDLockout,

    /// Authentication was canceled by application (e.g. invalidate was called while
    /// authentication was in progress).
    LAErrorAppCancel        NS_ENUM_AVAILABLE(10_11, 9_0) = kLAErrorAppCancel,

    /// LAContext passed to this call has been previously invalidated.
    LAErrorInvalidContext   NS_ENUM_AVAILABLE(10_11, 9_0) = kLAErrorInvalidContext
} NS_ENUM_AVAILABLE(10_10, 8_0);

你若觉得系统枚举过于复杂，你当然也可以自定义，我在封装的类中保留自定义枚举，方便修改。

封装类在使用的时候，直接调用方法即可，但是返回失败的时候需要自行判断。如下

- (void)clickTouchID
{
    [[MTTouchIdTool sharedInstance]evaluatePolicy:@"这是测试的Touch ID" fallbackTitle:@"输入密码" SuccesResult:^{
        NSLog(@"验证成功");
    } FailureResult:^(LAError result) {
        switch (result) {
            case LAErrorSystemCancel:
            {
                 NSLog(@"切换到其他APP");
                break;
            }
            case LAErrorUserCancel:
            {
                NSLog(@"用户取消验证Touch ID");
                
                break;
            }
            case LAErrorTouchIDNotEnrolled:
            {
                NSLog(@"TouchID is not enrolled");
                break;
            }
            case LAErrorUserFallback:
            {

                NSLog(@"用户选择输入密码");

                break;
            }
            default:
            {
  
                NSLog(@"其他情况");

                break;
            }
        
        }
    }];
}