Explain property observers in Swift.

Property observers monitor changes to a property's value and respond accordingly.\n\n• **Types of Observers:**\n• **willSet:** Called before value is stored\n• **didSet:** Called after value is stored\n\n\nclass StepCounter { \n var totalSteps: Int = 0 {\n willSet(newTotalSteps) {\n print("About to set totalSteps to \(newTotalSteps)")\n }\n didSet {\n if totalSteps > oldValue {\n print("Added \(totalSteps - oldValue) steps")\n }\n }\n }\n}\n\nlet stepCounter = StepCounter()\nstepCounter.totalSteps = 200\n// About to set totalSteps to 200\n// Added 200 steps\n\n\n• **Use Cases:**\n• Validation before setting values\n• Triggering UI updates\n• Logging changes\n• Maintaining data consistency\n• Synchronizing related properties\n\n• **Important Notes:**\n• Cannot be used with lazy properties\n• Not called during initialization\n• Available for stored properties only\n• Can access oldValue in didSet\n• Can access newValue in willSet