Ios 8 Touch ID 使用

Touch ID 介绍

参考：http://www.imore.com/touch-id-ios-8-explained

Touch ID API

前提：只有在装有iOS8的真机设备才能编译通过。

Step1). 使用Touch ID API,首先需要导入:LocalAuthentication.framework

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#import <LocalAuthentication/LAContext.h>

Step2). 使用API，我们需要创建一个Authentication Context

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

Step3). 检查当前Touch ID 是否可用,设备没有TouchID或者TouchID未开启返回false，有TouchID并开启返回true.

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  - (BOOL)canEvaluatePolicy:(LAPolicy)policy error:(NSError * __autoreleasing *)error;

Step4). 调用显示验证界面

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  - (void)evaluatePolicy:(LAPolicy)policy
         localizedReason:(NSString *)localizedReason
                     reply:(void(^)(BOOL success, NSError *error))reply;

localizedReason：根据官方文档必须提供.

reply:验证成功 success == YES, 否则返回error,根据error.code可以得到具体的原因.

在<LocalAuthentication/LAError.h>头文件中可以看到如下定义：

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  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,
  } NS_ENUM_AVAILABLE(10_10, 8_0);

Touch ID API 简单封装Demo

TouchIdUtil.h

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    typedef NS_ENUM(NSInteger, TouchIdEvaluateResult)
    {
        kTouchIdEvaluateResultSuccess,   // 验证成功
        kTouchIdEvaluateResultFailed,    // 验证失败
        kTouchIdEvaluateResultCancel,    // 点击取消按钮
        kTouchIdEvaluateResultFallback,  // 点击回退按钮
        kTouchIdEvaluateResultOther      // 未知结果
    };

    typedef void(^TouchIdEvaluateCallback)(TouchIdEvaluateResult result);

    @interface TouchIdUtil : NSObject

    + (instancetype)sharedInstance;

    // Touch Id 是否开启或设置
    - (BOOL)canEvaluatePolicy;

    // Touch Id 验证 callback回调已经抛到了主线程
    - (void)evaluatePolicy:(NSString *)localizedReasion
             fallbackTitle:(NSString *)title
                  callback:(TouchIdEvaluateCallback)cb;

    @end

TouchIdUtil.m

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#import "TouchIdUtil.h"
#import <LocalAuthentication/LocalAuthentication.h>

@implementation TouchIdUtil

+ (instancetype)sharedInstance
{
    static TouchIdUtil* instance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[TouchIdUtil alloc] init];
    });
    return instance;
}

- (BOOL)canEvaluatePolicy
{
    LAContext *context = [[LAContext alloc] init];
    NSError *error;
    return [context canEvaluatePolicy: LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error];
}

- (void)evaluatePolicy:(NSString *)localizedReasion
         fallbackTitle:(NSString *)title
              callback:(TouchIdEvaluateCallback)cb
{
    LAContext *context = [[LAContext alloc] init];
    if (title) {
        context.localizedFallbackTitle = title;
    }

    NSString *myLocalizedReasonString = localizedReasion;
    __weak typeof (self) weakSelf = self;
    [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
             localizedReason:myLocalizedReasonString
                       reply:
     ^(BOOL succes, NSError *error) {
         if (succes) {
             [[weakSelf class] reportResultOnUI:kTouchIdEvaluateResultSuccess callback:cb];
         } else {
             switch (error.code) {
                 case LAErrorAuthenticationFailed:
                     [[weakSelf class] reportResultOnUI:kTouchIdEvaluateResultFailed callback:cb];
                     break;
                 case LAErrorUserCancel:
                     [[weakSelf class] reportResultOnUI:kTouchIdEvaluateResultCancel callback:cb];
                     break;
                 case LAErrorUserFallback:
                     [[weakSelf class] reportResultOnUI:kTouchIdEvaluateResultFallback callback:cb];
                     break;
                 default:
                     [[weakSelf class] reportResultOnUI:kTouchIdEvaluateResultOther callback:cb];
                     break;
             }
         }
     }];
}

+ (void)reportResultOnUI:(TouchIdEvaluateResult)result callback:(TouchIdEvaluateCallback)cb
{
    dispatch_async(dispatch_get_main_queue(), ^{
        cb(result);
    });
}

@end

问题总结

1.指纹识别3次错误会弹出系统“输入密码”数字键盘，而且这3次错误机会是系统所有应用共享

2.不要在 evaluatePolicy:方法中调用 canEvaluatePolicy <LocalAuthentication/LAContext.h>中有说明

Demo 见：TouchIdTest

参考链接