Most Properties Are Backed by Instance Variables
You Can Customize Synthesized Instance Variable Names
As mentioned earlier, the default behavior for a writeable property is to use an instance variable called _propertyName.
If you wish to use a different name for the instance variable, you need to direct the compiler to synthesize the variable using the following syntax in your implementation:
@implementation YourClass
@synthesize propertyName = instanceVariableName;
...
@end
For example:
@synthesize firstName = ivar_firstName;
In this case, the property will still be called firstName, and be accessible through firstName and setFirstName: accessor methods or dot syntax, but it will be backed by an instance variable called ivar_firstName.
Important: If you use @synthesize without specifying an instance variable name, like this:
@synthesize firstName;
- the instance variable will bear the same name as the property.
- In this example, the instance variable will also be called
firstName, without an underscore.