ios开发（八）：property
property的作用就是为变量产生一个get一个set，一个property使用由两个部分组成，一个是声明一个是定义，
声明的结构：
@property (attributes) type name;
nonatomic. 告诉编译器不用保证线程安全。
readonly. 只可读，这个很好理解，也就是只有get，没有set。
readwrite. 这个是默认的方式。
assign. 直接用等于号赋值，这个也是默认方式。
copy. 使用object自己的拷贝函数而不是assign。
iOS 5 中对属性的设置新增了strong 和weak关键字来修饰属性
strong 用来修饰强引用的属性；
@property (strong) SomeClass * aObject;对应原来的
@property (retain) SomeClass * aObject; 和 @property (copy) SomeClass * aObject;
weak 用来修饰弱引用的属性；
@property (weak) SomeClass * aObject;
对应原来的
@property (assign) SomeClass * aObject;
@property (nonatomic, copy) NSString* name
can be realized by the compiler as follows:
-(NSString*) name{returnname;
}
-(void) setName:(NSString*) aName{
if(name!= aName){[name release];name = [aName copy];
}}
@property (nonatomic, retain) Employee* manager
can be realized by the compiler as follows:
-(Employee*) manager{returnmanager;
}
-(void) setManager:(Employee*) theManager{if(manager!= theManager){
[manager release];
manager = [theManager retain];
}
}
@property (nonatomic, assign) NSString* address
can be realized by the compiler as follows:
-(NSString*) address{returnaddress;
}
-(void) setAddress:(NSString*)anAddress{
address = anAddress;
}
@property (nonatomic, copy) NSMutableArray* achievements
When dealing with mutable collections such asNSMutableArray,the compiler-providedsetter/getter might not be appropriate. Let us see a possible synthesis of theachievementsproperty:
-(NSMutableArray*) achievements{returnachievements;
}
-(void) setAchievements:(NSMutableArray*) newAchievements{
if(achievements!= newAchievements){[achievements release];
achievements = [newAchievements copy];
}}