In Objective-C, declared properties are a convenient way to replace the declaration and manual implementation of accessor methods for objects.
A property declaration begins with the keyword @property. You can decorate a property with attributes by using the form @property(attribute [, attribute2, ...]).
You use the @synthesize directive to tell the compiler that it should synthesize the setter and/or getter methods for a property if you do not supply them within the @implementation block. The @synthesize directive also synthesizes an appropriate instance variable if it is not otherwise declared.
Declared properties provide a useful simplification of the usual requirement to explicitly declare all accessor methods, in the following ways (excerpt from Apple documentation on Declared Properties):
- The property declaration provides a clear, explicit specification of how the accessor methods behave.
- The compiler can synthesize accessor methods for you, according to the specification you provide in the declaration.
- Properties are represented syntactically as identifiers and are scoped, so the compiler can detect use of undeclared properties.
Questions relating to the proper use of @property declarations, @synthesize, and the use of dot notation to assign values to these properties (object.propertyName = propertyValue;) should use this tag.
Further reading:
