Ivar vs Property

Concepts

In the field of runtime, there are four concepts about this issue:

Reference Type	Struct Type	Description
Method	objc_method	An opaque type that represents a method in a class definition.
Ivar	objc_ivar	An opaque type that represents an instance variable.
Category	objc_category	An opaque type that represents a category.
objc_property_t	objc_property	An opaque type that represents an Objective-C declared property.

Ivar vs Property

	Ivar	Property
nonatomic	❌	✅
copy	❌	✅
@protected	✅	❌
@ package	✅	❌

参考

• Reason to use ivars vs properties in objective c – Stack Overflow
• objective c – Why would you use an ivar? – Stack Overflow
• Objective-C: properties vs ivars – Rollout.io Blog
• Difference between iVar and Property. – iPhone Dev SDK
• Private properties, methods and ivars in Objective-C
• Ram’s Blog • iOS: Property vs Instance Variable
• Slick’s Definitive Guide To Properties – iPhone Dev SDK