objective-c - 成员变量如何赋值的

Question

我们都知道属性的赋值是调用属性的setter方法, 可是成员变量是如何赋值的呢? 他的内部实现原理是什么?

Answer 1

@implementation ViewController

{
    UIView *_iconView;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    NSLog(@"%@", self->_iconView);
    NSLog(@"%@", _iconView);
}

Answer 2

I think I want to ask about the difference between ivar and property.
property = ivar+getter+setter

For example
property (assign) int a will generate a member variable of _a by default, which we call ivar
At the same time, a setter method will be generated, which looks like this:

-(void)setA:(int)a {
    _a = a;
}

A getter method will also be generated, which looks like this:

-(int)a {
    return _a;
}

At the same time, it will give _a some gain buffs, such as strong strong reference and weak weak reference to control the life cycle of this variable.

So property is just a form of programming, you don’t need to pay too much attention to it, you can completely follow your own routine.