blocks|key|225223|text|可以在其中一个对象中使用弱赋值设置循环引用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|225224|ObjectA.h|225225|@class+ObjectB
@interface+ObjectA
@property+(strong)+ObjectB+*parent;
@end|code-block|syntax|javascript|225226|ObjectA.m|225227|#import+"ObjectA.h"
#import+"ObjectB.h"
@implementation+ObjectA
//+methods
@end|225228|ObjectB.h|225229|@class+ObjectA
@interface+ObjectB
@property+(weak)+ObjectA+*child;
@end|225230|ObjectB.m|225231|#import+"ObjectB.h"
#import+"ObjectA.h"
@implementation+ObjectB
//+methods
@end|225232|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|11|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|Q|3|R|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|T|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

You can set up circular references using weak assignment in one of the objects:

ObjectA.h

<pre><code>@class ObjectB
@interface ObjectA
@property (strong) ObjectB *parent;
@end
</code></pre>

ObjectA.m

<pre><code>#import "ObjectA.h"
#import "ObjectB.h"
@implementation ObjectA
// methods
@end
</code></pre>

ObjectB.h

<pre><code>@class ObjectA
@interface ObjectB
@property (weak) ObjectA *child;
@end
</code></pre>

ObjectB.m

<pre><code>#import "ObjectB.h"
#import "ObjectA.h"
@implementation ObjectB
// methods
@end
</code></pre>

blocks|key|417771|text|创建自定义委托，并从一个类向另一个类发送消息。因此，行为将是一个类将是发送者，另一个将是接收者。供参考如下：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|417772|iOS+Protocol+/+Delegate+confusion?|offset|length|417773|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/19679216/ios-protocol-delegate-confusion/19679547#19679547^0|0|0|Y|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

Create the custom delegate and send messages from one class to another. So that the behavior will be one class will be sender and other will be reciever. For reference follow this:-

<a href="https://stackoverflow.com/questions/19679216/ios-protocol-delegate-confusion/19679547#19679547">iOS Protocol / Delegate confusion?</a>

blocks|key|225256|text|我不认为这是一个好的编程风格，但您可以使用单例在许多不同的类之间共享数据。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|225257|就像这样:+Singleton.h|225258|@interface+Settings+:+NSObject
@property+(nonatomic)+NSString+*mySharedString;
%2B+(Settings+*)my;
-+(id)init;
@end|code-block|syntax|javascript|225259|Singleton.m|225260|#import+"Settings.h"
@implementation+Settings
@synthesize+mySharedString
static+Settings+*my+=+nil;
%2B+(Settings+*)my
{
++if+(!my)
++++my+=+[Settings+new];
++return+my;
}

-+(id)init
{
+++self+=+[super+init];
+++if+(self){
+++++//do+some+code
+++}
+++return+self
}
@end|225261|然后在任何一堂课上你都可以说|225262|NSString+*classString+=+[Settings+my].mySharedString|225263|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I don't think this is a good programming style but you could use singleton to share data between many different classes

Like that:
Singleton.h

<pre><code>@interface Settings : NSObject
@property (nonatomic) NSString *mySharedString;
+ (Settings *)my;
- (id)init;
@end
</code></pre>

Singleton.m

<pre><code>#import "Settings.h"
@implementation Settings
@synthesize mySharedString
static Settings *my = nil;
+ (Settings *)my
{
 if (!my)
 my = [Settings new];
 return my;
}

- (id)init
{
 self = [super init];
 if (self){
 //do some code
 }
 return self
}
@end
</code></pre>

And then in any class you can say something like

<pre><code>NSString *classString = [Settings my].mySharedString
</code></pre>

blocks|key|225271|text|我觉得你倒过来了。父母应该知道孩子的事。孩子不需要知道父母的情况。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|225272|父级可以强烈引用其子级。(X)|225273|//inside+the+parent+class
@property+(nonatomic,+strong)+id+childObject;|code-block|syntax|javascript|225274|子对象通常不会清楚地知道它的“父”是什么，但是它对委托的引用会很弱。该委托可以是特定类型的类，也可以是符合特定协议的类型id的泛型类。(X)|offset|length|style|CODE|225275|//inside+the+child+class
@property+(nonatomic,+weak)+id<SomeProtocol>+delegate;|225276|entityMap^0|0|0|0|1O|2|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@$K|W|L|X|M|N]]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I think you've got it backwards. The the parent IS supposed to know about the child. The child should not need to know about its parent. 

The parent can have a strong reference to its child. (ex)

<pre><code>//inside the parent class
@property (nonatomic, strong) id childObject;
</code></pre>

The child commonly will not know explicitly what its "Parent" is, but it will have a weak reference to a delegate. That delegate can either be a specific type of class, or a generic class of type <code>id</code> that conforms to a particular protocol. (ex)

<pre><code>//inside the child class
@property (nonatomic, weak) id&lt;SomeProtocol&gt; delegate;
</code></pre>

blocks|key|226521|text|要将数据(对象或值)从推送或表示ViewControllerB的ViewControllerA转发到ViewControllers，您需要执行如下操作：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|226522|(例如，将NSString从ViewControllerA传递给ViewControllerB+)|226523|在没有存储板的情况下向前传递数据:|BOLD|226524|ViewControllerB+*viewControllerB+=+[[ViewControllerB+alloc]+initWithNib:@"ViewControllerB"+bundle:nil];
viewControllerB.aString+=+myString;+//+myString+is+the+data+you+want+to+pass
[self+presentViewController:viewControllerB+animated:YES+completion:nil];|code-block|syntax|javascript|226525|使用UINavigationController：|226526|ViewControllerB+*viewControllerB+=+[[ViewControllerB+alloc]+initWithNib:@"ViewControllerB"+bundle:nil];
viewControllerB.aString+=+myString;
[self.navigationController+pushViewController:viewControllerB+animated:YES];|226527|在viewControllerB内部，您需要在.h上有一个@property，例如：|226528|@property+(nonatomic,+strong)+NSString+*aString;|226529|在您的.m中，您可以检索这个@property：|226530|-+(void)viewWillAppear:(BOOL)animated
{
++++[super+viewWillAppear:animated];

++++NSLog(@"%25@",+_aString);
}|226531|这是一个使用NSString的示例，但是您可以传递任何对象。|226532|entityMap^0|G|F|W|F|0|E|F|W|F|0|0|H|0|0|2|M|0|0|1|F|T|9|0|0|E|9|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@$9|16|A|17|B|C]|$9|18|A|19|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1A|8|@$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1F|8|@$9|1G|A|1H|B|J]]|D|@]|E|$]]|$1|K|3|L|5|M|7|1I|8|@]|D|@]|E|$N|O]]|$1|P|3|Q|5|6|7|1J|8|@$9|1K|A|1L|B|C]]|D|@]|E|$]]|$1|R|3|S|5|M|7|1M|8|@]|D|@]|E|$N|O]]|$1|T|3|U|5|6|7|1N|8|@$9|1O|A|1P|B|C]|$9|1Q|A|1R|B|C]]|D|@]|E|$]]|$1|V|3|W|5|M|7|1S|8|@]|D|@]|E|$N|O]]|$1|X|3|Y|5|6|7|1T|8|@$9|1U|A|1V|B|C]]|D|@]|E|$]]|$1|Z|3|10|5|M|7|1W|8|@]|D|@]|E|$N|O]]|$1|11|3|12|5|6|7|1X|8|@]|D|@]|E|$]]|$1|13|3|-4|5|6|7|1Y|8|@]|D|@]|E|$]]]|14|$]]

To pass data (object or value) forward to a <code>ViewControllerB</code> from a <code>ViewControllerA</code> pushing or presenting ViewControllers, you need to do something like this :

(for example, pass a NSString to a <code>ViewControllerB</code> from a <code>ViewControllerA</code>) 

Passing data forward without Storyboard :

<pre><code>ViewControllerB *viewControllerB = [[ViewControllerB alloc] initWithNib:@"ViewControllerB" bundle:nil];
viewControllerB.aString = myString; // myString is the data you want to pass
[self presentViewController:viewControllerB animated:YES completion:nil];
</code></pre>

Using <code>UINavigationController</code> :

<pre><code>ViewControllerB *viewControllerB = [[ViewControllerB alloc] initWithNib:@"ViewControllerB" bundle:nil];
viewControllerB.aString = myString;
[self.navigationController pushViewController:viewControllerB animated:YES];
</code></pre>

and inside <code>viewControllerB</code>, you need to have a <code>@property</code> on your .h like :

<pre><code>@property (nonatomic, strong) NSString *aString;
</code></pre>

and inside your .m, you retrieve this <code>@property</code> :

<pre><code>- (void)viewWillAppear:(BOOL)animated
{
 [super viewWillAppear:animated];

 NSLog(@"%@", _aString);
}
</code></pre>

This is an example with a NSString, but you can pass any object.

blocks|key|452633|text|您负责在视图控制器之间传递数据。您可以使用-parentViewController或-childViewControllers，也可以使用weak引用进行循环引用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|452634|如果您使用的是故事板，也许看看-performSegueWithIdentifier:sender:是个好主意。发送方可用于在视图控制器之间传递数据。|452635|此外，如果您使用故事板，有时-+instantiateViewControllerWithIdentifier:是很方便的事情。|452636|有不止一种方法可以做到这一点。|452637|entityMap^0|L|L|17|L|1Y|4|0|F|Z|0|E|16|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|10|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|M|$]]

You are in charge of passing data between view controller. You can use <code>-parentViewController</code> or <code>-childViewControllers</code>, you also can make circular references using <code>weak</code> references.

If you are using storyboard maybe it will be a good idea to take a look at <code>-performSegueWithIdentifier:sender:</code>. Sender can be used to pass data between view controller. 

Also if you are using storyboard, sometimes <code>- instantiateViewControllerWithIdentifier:</code> is handy thing.

There is more than one way to do that.

I'm having a hard time understanding how parents and children communicate (and how they pass data to each-other). I have two simple objects (two ViewControllers). I understand that the parent-child relationship should allow me to pass two variables from the child object into the parent object using properties. Since I included Obj. B into Obj A I assume that A is the parent and B is the child. I also understand that the child knows about the parent but not vice-versa, is that correct? 

I included Obj. B into Obj. A and I was hoping to have access to a few variables I have declared in the header file of Obj. B

Could somebody give me a very simple example and help me put an end to my confusion? Thanks much.

Passing data into an object using properties in Obj.C

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我很难理解父母和孩子是如何沟通的(以及他们如何相互传递数据)。我有两个简单的对象(两个ViewControllers)。我理解父-子关系应该允许我使用属性将两个变量从子对象传递到父对象。因为我包括了Obj。B进入Obj A，我假设A是父母，B是孩子。我也知道孩子知道父母，反之亦然，对吗？我也包括了。B转入Obj。A和我...

问使用Obj.C中的属性将数据传递到对象
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