iOS 8 SDK by Apple provides Local Authentication API that allows developers to integrate Touch Id authentication in applications.

To integrate Touch Id authentication follow the below steps:

• Import Local Authentication framework in your controller.
              import LocalAuthentication
• Use the following function to the authentic user:

 func authenticateUser(){
        let authenticationContext = LAContext()
        var error:NSError?
        
        // 2. Check if the device has a fingerprint sensor
        // If not, show the user an alert view and bail out!
        
guard authenticationContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) else {

            // SHOW MESSAGE HERE
            return
            
        }
        
        // 3. Check the fingerprint
        authenticationContext.evaluatePolicy(
            .deviceOwnerAuthenticationWithBiometrics,
            localizedReason: "Identify Yourself",
            reply: { [unowned self] (success, error) -> Void in
                
                if( success ) {
                    // Fingerprint recognized
                    // The success code goes here
                                   
                }else {
                        // Check if there is an error
                    if let error = error {
                       // Error Occured
                      // The error code goes here
                    }
                    
                }
                
            })
        
    }