//iOS8.0后才支持指紋識別接口
 if ([UIDevice currentDevice].systemVersion.floatValue < 8.0) {
  return;
 }

- (void)evaluateAuthenticate
{
 //創建LAContext
 LAContext* context = [[LAContext alloc] init];
 NSError* error = nil;
 NSString* result = @"請驗證已有指紋";
 
 //首先使用canEvaluatePolicy 判斷設備支持狀態
 if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {
  //支持指紋驗證
  [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:result reply:^(BOOL success, NSError *error) {
   if (success) {
    //驗證成功，主線程處理UI
   }
   else
   {
    NSLog(@"%@",error.localizedDescription);
    switch (error.code) {
     case LAErrorSystemCancel:
     {
      //系統取消授權，如其他APP切入
      break;
     }
     case LAErrorUserCancel:
     {
      //用戶取消驗證Touch ID
      break;
     }
     case LAErrorAuthenticationFailed:
     {
      //授權失敗
      break;
     }
     case LAErrorPasscodeNotSet:
     {
      //系統未設置密碼
      break;
     }
     case LAErrorTouchIDNotAvailable:
     {
      //設備Touch ID不可用，例如未打開
      break;
     }
     case LAErrorTouchIDNotEnrolled:
     {
      //設備Touch ID不可用，用戶未錄入
      break;
     }
     case LAErrorUserFallback:
     {
      [[NSOperationQueue mainQueue] addOperationWithBlock:^{
       //用戶選擇輸入密碼，切換主線程處理
       
      }];
      break;
     }
     default:
     {
      [[NSOperationQueue mainQueue] addOperationWithBlock:^{
       //其他情況，切換主線程處理
      }];
      break;
     }
    }
   }
  }];
 }
 else
 {
  //不支持指紋識別，LOG出錯誤詳情
  NSLog(@"不支持指紋識別");
  
  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);
 }
}