Too hard! OC in agreement on understanding and trust

I say it is difficult for me this beginner, ha ha. OC commission saw a few days, check the information is still very confused, I do not know following this understanding is correct. Please advice

 
# Import  
# Import "TView.h" 
# Import "TActive.h" 
int main (int argc, const char * argv []) 
{

@ Autoreleasepool {

TView * v = [[TView alloc] init]; 
TActive * a = [[TActive alloc] init]; 
a.tView = v; 
v.Delegate = a; 
[V onClick]; 

} 
return 0; 
} 

TView.h file: 

@ Protocol Message  
- (Void) onClickMsg; 
@ End 

@ Interface TView: NSObject  
{
NSString * TViewText; 
id  Delegate; 

} 
@ Property (nonatomic, retain) id  Delegate; 
@ Property (nonatomic, retain) TView * TviewText; 
- (Void) onClick; 
- (TView *) init; 
- (Void) Show; 
@ End 


TView.m file: 

# Import "TView.h" 

@ Implementation TView 
@ Synthesize Delegate; 
@ Synthesize TviewText; 

- (TView *) init 
{
self = [super init]; 
if (self) 
{
NSLog (@ "Internet please click me"); 
} 
return self; 
} 

- (Void) onClick 
{
NSLog (@ "button is clicked."); 

[Delegate onClickMsg]; 

} 

- (Void) Show 
{
NSLog ("download data from the Internet, I will show it." @); 
NSLog (@ "to download data from the Internet is:% @", TviewText); 
NSLog (@ "Show finished Thank you for using goodbye.!"); 
} 
@ End 

TActive.h file 

# Import  
# Import "TView.h" 

@ Interface TActive: NSObject  
{
TView * tView; 
} 

@ Property (nonatomic, retain) TView * tView; 
@ End 

TActive.m file 

# Import "TActive.h" 

@ Implementation TActive 
@ Synthesize tView; 

- (Void) onClickMsg 
{

NSLog (@ "to download data from the Internet."); 
NSLog (@ "downloaded data are: China"); 
[TView setTviewText: @ "China"]; 
NSLog (@ "the download is complete."); 
[TView Show]; 
} 

@ End 

Reply:
Results of operation:
2012-04-20 16:15:20.953 Day8 [233:403] online, please click on my
2012-04-20 16:15:20.989 Day8 [233:403] button is clicked.
2012-04-20 16:15:20.993 Day8 [233:403] download data from the Internet.
2012-04-20 16:15:20.995 Day8 [233:403] downloaded data are: China
2012-04-20 16:15:20.998 Day8 [233:403] downloaded.
2012-04-20 16:15:21.001 Day8 [233:403] data downloaded from the Internet. I will show it
2012-04-20 16:15:21.003 Day8 [233:403] data downloaded from the Internet are: China
2012-04-20 16:15:21.005 Day8 [233:403] Thank you for the use of the display is completed. Goodbye!


Reply:
A and B signed an agreement to abide by A and B, the agreement is to allow Party B to provide the data downloaded from the Internet.
Reply:
Ah, nearly what it means.
Reply:
Ah, nearly what it means.
Reply:
The so-called commission is a design pattern is probably one thing to another person handed down.
For example, your boss will receive a corporate job, then ye programmer to complete.
You do not write it and protocols confused.
http://blog.langyufei.com/?p=273
You look at it.
Reply:
Who defined the protocol, who implement the protocol. Understood, there is the case. Write more than just fine
Reply:
@ Interface TView: NSObject
Here do not add , why use agreement, a program looks to make it easier to understand, and the other is to regulate, for example, if there is @ require the agreement of the method, then implement the protocol class must implement this @ require methods, so you can guarantee will be commissioned to do some things (because you use entrust certainly want him to achieve some behavior)
Are generally entrusted to implement the protocol, @ interface TActive: NSObject , here is entrusted to achieve agreement and TView this class is to use a delegate class, so do not realize
Reply:
White said the agreement is a contract. Both sides need to comply with an interactive constraints. The mentioned here is the "Agency Agreement" concept, which should be a decoupling of objects interact to solve a design pattern. For example, the following scenario: There are two objects A and B, A B needs to call a method in a way, we usually add pointers application of B in A, this is no problem, but we might also object B's A method to call, if it is according to this design, it is likely there will be a circular reference.
In fact, nothing more than objects assume two roles in the process of interaction, a Data receiver, 2. Data sender. In the "Agency Agreement" model, the data transmitted by the data receiver comprises a pointer.
@ Interface MyWidget: BaseWidget {
id delegate;
}
@ Property (assign) id delegate;
@ End

The recipient of the data is required to achieve agreement
@ Protocal BaseWidgetDelegate;
@ Interface WidgetManager: NSObject
....
@ End


Reply:
Applications, the agent for the OC in the system, will call on it, some of the functions entrusted to Apple to achieve (packaged), is a pointer object by value handwritten agency essentially Well, to call themselves to design their own (own realization)

Remember the agent slowly to understand format is also a choice

Personal opinion