简单实现iOS指纹解锁(TouchID)

//iOS8.0后才支持指纹识别接口
 if ([UIDevice currentDevice].systemVersion.floatValue < 8.0) {
  return;
 }

- (void)evaluateAuthenticate
{
 //创建LAContext
 LAContext* context = [[LAContext alloc] init];
 NSError* error = nil;
 NSString* result = @"请验证已有指纹";
 
 //首先使用canEvaluatePolicy 判断设备支持状态
 if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {
  //支持指纹验证
  [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:result reply:^(BOOL success, NSError *error) {
   if (success) {
    //验证成功，主线程处理UI
   }
   else
   {
    NSLog(@"%@",error.localizedDescription);
    switch (error.code) {
     case LAErrorSystemCancel:
     {
      //系统取消授权，如其他APP切入
      break;
     }
     case LAErrorUserCancel:
     {
      //用户取消验证Touch ID
      break;
     }
     case LAErrorAuthenticationFailed:
     {
      //授权失败
      break;
     }
     case LAErrorPasscodeNotSet:
     {
      //系统未设置密码
      break;
     }
     case LAErrorTouchIDNotAvailable:
     {
      //设备Touch ID不可用，例如未打开
      break;
     }
     case LAErrorTouchIDNotEnrolled:
     {
      //设备Touch ID不可用，用户未录入
      break;
     }
     case LAErrorUserFallback:
     {
      [[NSOperationQueue mainQueue] addOperationWithBlock:^{
       //用户选择输入密码，切换主线程处理
       
      }];
      break;
     }
     default:
     {
      [[NSOperationQueue mainQueue] addOperationWithBlock:^{
       //其他情况，切换主线程处理
      }];
      break;
     }
    }
   }
  }];
 }
 else
 {
  //不支持指纹识别，LOG出错误详情
  NSLog(@"不支持指纹识别");
  
  switch (error.code) {
   case LAErrorTouchIDNotEnrolled:
   {
    NSLog(@"TouchID is not enrolled");
    break;
   }
   case LAErrorPasscodeNotSet:
   {
    NSLog(@"A passcode has not been set");
    break;
   }
   default:
   {
    NSLog(@"TouchID not available");
    break;
   }
  }
  
  NSLog(@"%@",error.localizedDescription);
 }
}