Objective-C在两个按钮之间切换

I'm new to Objective-C, and I'm trying to create an app with two buttons that toggle off and on in tandem. I've handled the button states (images for on and off) in Interace Bulder, but I'm having trouble figuring out exactly how to write the logic in Xcode. I'm new to Objective-C, and I'm trying to creat