Objective c 如何使接口实例符合id<；类型的协议&燃气轮机；

我正在学习objective-c，我正在努力学习@protocol。我开发了下面的示例。但我不清楚的是 main_1和main_2中的代码。对于main_1，我认为它可能或多或少类似于java，例如，*sampleClass是sampleClass的实例，因此，它不应该访问ProcessComplete方法。然而，在Objective-c中，代码是有效的

对于main_2，我试图实例化包含SampleClass的SampleClass对象作为协议的实现者。与main_1中的代码不同，我假设或认为main_1中的代码是SampleClass的提供实例，但不是协议的实现者

如果我不对，请纠正我。 2-请让我知道为什么在代码main_2中，我收到以下错误：

Implicit conversion of an Objective-C pointer to '__strong id<PrintClientProtocol> *' is disallowed with ARC
Pointer to non-const type 'id<PrintClientProtocol>' with no explicit ownership
Incompatible pointer types initializing '__strong id<PrintClientProtocol> *' with an expression of type 'SampleClass *'

main_2

    id<PrintClientProtocol> *sampleClass2 = [[SampleClass alloc] init];
    [sampleClass2 startAction];
    [sampleClass2 processCompleted];

printClass.m

#import <Foundation/Foundation.h>
#import "PrintClass.h"
#import "SampleClass.h"

@implementation PrintClass

- (void) printDetails {
    NSLog(@"Printing Details");
    [implementor processCompleted];
}

- (void) setDelegate:(id)newDelegate {
    implementor = newDelegate;
}

@end

#import <Foundation/Foundation.h>
#import "SampleClass.h"
#import "PrintClass.h"

@implementation SampleClass

-(void)startAction {
    PrintClass *printClass = [[PrintClass alloc] init];
    [printClass setDelegate: self];
    [printClass printDetails];
}

-(void) processCompleted {
    NSLog(@"PROCESS_COMPLETED.....");
}

@end

#导入
#导入“PrintClass.h”
#导入“SampleClass.h”
@实现PrintClass
-（作废）打印详细信息{
NSLog（“打印详细信息”）；
[实现者进程完成]；
}
-（void）setDelegate:（id）newDelegate{
implementor=newDelegate；
}
@结束

SampleClass.h

#ifndef PrintClass_h
#define PrintClass_h
#endif /* PrintClass_h */

//The class/interface that to execute the protocols in the client contract. execution is to be done according
//to the DELEGATE Class/Interface
@interface PrintClass :NSObject {
   id implementor;//instance of the DELEGATE/implementor and executor class/interface
    //change id to SampleClass for testing
}

- (void) printDetails;
- (void) setDelegate: (id) implementor;

@end

#ifndef SampleClass_h
#define SampleClass_h


#endif /* SampleClass_h */
#import "PrintClientProtocol.h"
//the class/interface that provide implementions and execution of it, which is the "DELEGATE"
@interface SampleClass : NSObject<PrintClientProtocol>
- (void)startAction;
@end

\ifndef样本类
#定义样本类
#endif/*样本类*/
#导入“PrintClientProtocol.h”
//提供实现和执行的类/接口，即“委托”
@接口示例类：NSObject
-（无效）startAction；
@结束

SampleClass.m

#import <Foundation/Foundation.h>
#import "PrintClass.h"
#import "SampleClass.h"

@implementation PrintClass

- (void) printDetails {
    NSLog(@"Printing Details");
    [implementor processCompleted];
}

- (void) setDelegate:(id)newDelegate {
    implementor = newDelegate;
}

@end

#import <Foundation/Foundation.h>
#import "SampleClass.h"
#import "PrintClass.h"

@implementation SampleClass

-(void)startAction {
    PrintClass *printClass = [[PrintClass alloc] init];
    [printClass setDelegate: self];
    [printClass printDetails];
}

-(void) processCompleted {
    NSLog(@"PROCESS_COMPLETED.....");
}

@end

#导入
#导入“SampleClass.h”
#导入“PrintClass.h”
@实现示例类
-（无效）startAction{
PrintClass*PrintClass=[[PrintClass alloc]init]；
[printClass setDelegate:self]；
[printClass printDetails]；
}
-（作废）处理完成{
NSLog（@“流程完成…”）；
}
@结束

PrintClientProtocol：

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

//the protocol that demands or needs implementor and executor "Client/Delegatee Protocol"
@protocol PrintClientProtocol <NSObject>
- (void) processCompleted;
@end

NS_ASSUME_NONNULL_END

#导入
NS\u假设\u非空\u开始
//要求或需要实施者和执行者的协议“客户机/被授权者协议”
@协议PrintClientProtocol
-（无效）已完成；
@结束
NS\u假设\u非空\u结束

类的声明

SampleClass

表示它符合协议

PrintClientProtocol

。这意味着它会自动继承协议

PrintClientProtocol

中声明的所有成员，包括

-processCompleted

。这与您在Java中所期望的相同

在

main_2

中，问题在于类型

id

已经是指向对象类型的指针，类似于

SampleClass*

。通过编写

id*

，您正在编写指向对象类型指针的指针，该指针与右侧不兼容，右侧有指向对象类型的指针