如何在另一个视图（目标c）中传递更改变量的值？
有两个控制器
我在 view1.hi 中
NSString *bg;
@interface Lottery5ViewController : UIViewController {...}
，在 view2.mi 有，
-(IBAction) switchView2{
self.bg = @"blueButton.png";
}
但它无法编译并说 请求非结构或联合中的成员“bg”
我只想从 view2 修改 view1 中变量的值
i have two controller
in view1.h i have
NSString *bg;
@interface Lottery5ViewController : UIViewController {...}
in view2.m i have
-(IBAction) switchView2{
self.bg = @"blueButton.png";
}
but it cannot compile and said
request for member 'bg' in something not a structure or union
i just want to modify the value of a variable in view1 from view2
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您的问题是，在
view2的switchView2方法中，您正在调用self并尝试更改 ivar （或属性，不确定它是哪个）从显示的代码来看）是一个不同类。如果您想将某些内容从一个实例发送到另一个实例，您必须首先在它们之间建立某种连接。有几种方法可以让他们开口说话。能够传递此类内容的更好方法是设置委托协议或使用通知，然后view2可以调用在view1中进行更改的委托方法或发布一条通知，view1将被注册，以便它可以进行更改。实现此目的不太理想的方法是为view2提供一个 ivar（或属性），即view1。然后您就可以使用类似view1.bg = @"blueButton.png";的内容。Your problem is that in
view2'sswitchView2method you are callingselfand trying to change an ivar (or property, not sure which it is from the code shown) of a different class. If you want to send something from one instance to another you have to establish some sort of connection between them first. There are a few ways you can get them talking. The better ways to be able to pass something like this is to set up a delegate protocol or use notifications, thenview2could call the delegate method that makes the change inview1or post a notification thatview1would be registered for so that it could make the change. The less desirable way to accomplish this would be to giveview2an ivar (or property) that isview1. You would then be able to use something likeview1.bg = @"blueButton.png";.