Question

因此,奥杰奇-C和I m现在刚刚学会使用<条码>@property和<条码>@synthesize,用于变量,我当时正在问,我如何利用变量。我是否应该通过<条码>[自发]或<条码>自行查阅。这表明了我对法典的质疑:

@property (nonatomic, strong) UILabel *lbl;
...
@synthesize lbl = _lbl;

-(void) doStuff
{
   // How should I acces label?
   _lbl.text = @"A";
   [self lbl].text = @"B";
   self.lbl.text = @"C";
}

Answer 1

There is no difference here :

UILabel * l = [self lbl];  // ==   UILablel *l = self.lbl;
[self setLbl:l];          //  ==   self.lbl = l;

但是,你们的样本有不同之处:

_lbl.text = @"A";

That last one is not good because you are accessing the iVar directly bypassing your @property, which often don t make sense to do if you have declare it as @property.
In your case you are changing a property on your iVar, so there is no harm, but if you would do this :

_lbl = [[[UILabel alloc] initWithFrame:aRect] autorelease];

that would cause you a big problem, because you would have bypass the "setter". A strong setter would have retain that object, but now it s retain by no one, it will go away and you will have a bad pointer, that can make your application crash.

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