//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); }}