实例讲解设计模式中的命令模式在iOSApp开发中的运用

//
//  NimoCommand.h
//  CommandDemo
//
 
#import
 
@protocol NimoCommand
 
- (void)execute;
 
@end

//
//  NimoConcreteCommand.h
//  CommandDemo
//
#import
#import "NimoCommand.h"
@class NimoReceiver;
 
@interface NimoConcreteCommand : NSObject
 
@property (nonatomic) NimoReceiver *receiver;
 
- (id)initWithReceiver:(NimoReceiver *)receiver;
 
@end

//
//  NimoConcreteCommand.m
//  CommandDemo
//
 
#import "NimoConcreteCommand.h"
#import "NimoReceiver.h"
 
 
@implementation NimoConcreteCommand
 
- (void)execute
{
    [_receiver action];
}
 
- (id)initWithReceiver:(NimoReceiver *)receiver
{
    if (self = [super init]) {
        _receiver = receiver;
    }
    
    return self;
}
 
@end

//
//  NimoReceiver.h
//  CommandDemo
//

#import
 
@interface NimoReceiver : NSObject
 
- (void)action;
 
@end

//
//  NimoReceiver.m
//  CommandDemo
//

#import "NimoReceiver.h"
 
@implementation NimoReceiver
 
- (void)action
{
    NSLog(@"实际执行");
}
 
@end

//
//  NimoInvoker.h
//  CommandDemo
//
 
#import
#import "NimoCommand.h"
 
@interface NimoInvoker : NSObject
 
@property (nonatomic, weak) id command;
 
- (void)executeCommand;
 
@end

//
//  NimoInvoker.m
//  CommandDemo
//
 
#import "NimoInvoker.h"
 
 
@implementation NimoInvoker
 
- (void)executeCommand
{
    [_command execute];
}
 
@end

//
//  main.m
//  CommandDemo
//

#import
#import "NimoReceiver.h"
#import "NimoInvoker.h"
#import "NimoConcreteCommand.h"
 
int main(int argc, const char * argv[]) {
    @autoreleasepool {
       
        NimoReceiver *receiver = [[NimoReceiver alloc] init];
        NimoConcreteCommand *command = [[NimoConcreteCommand alloc] initWithReceiver:receiver];
        
        NimoInvoker *invoker = [[NimoInvoker alloc] init];
        invoker.command = command;
        [invoker executeCommand];
        
    }
    return 0;
}

2015-08-13 22:49:56.412 CommandDemo[1385:43303] 实际执行

//
//  NimoReceiver.h
//  InvocationDemo
//

#import
 
@interface NimoReceiver : NSObject
 
- (int)printWithName:(NSString *)name gender:(NSString *)gender age:(int)age;
 
@end

//
//  NimoReceiver.m
//  InvocationDemo
//

#import "NimoReceiver.h"
 
@implementation NimoReceiver
 
- (int)printWithName:(NSString *)name gender:(NSString *)gender age:(int)age
{
    NSLog(@"My name is %@, %@, %d years old.", name, gender, age);
    return 119;
}
 
@end

//
//  main.m
//  InvocationDemo
//

#import
#import "NimoReceiver.h"
 
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        //用Receiver的实例创建NSInvocation对象，并把Receiver的action作为选择器
        NimoReceiver *receiver = [[NimoReceiver alloc] init];
        NSString *name = @"Lee";
        NSString *gender = @"male";
        int age = 28;
        SEL sel = @selector(printWithName:gender:age:);
        NSMethodSignature *methodSignature = [[receiver class] instanceMethodSignatureForSelector:sel];
        NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:methodSignature];
        [invocation setTarget:receiver];
        [invocation setSelector:sel];
        [invocation setArgument:&name atIndex:2];
        [invocation setArgument:&gender atIndex:3];
        [invocation setArgument:&age atIndex:4];
        [invocation retainArguments];
        [invocation invoke]; //通过调用NSInvocation对象的invoke方法，完成对Receiver中action的调用
        
        int returnValue = 0;
        [invocation getReturnValue:&returnValue];
        
        NSLog(@"returnValue: %d", returnValue);
    }
    return 0;
}

2015-08-14 13:37:44.162 InvocationDemo[1049:36632] My name is Lee, male, 28 years old.
2015-08-14 13:37:44.164 InvocationDemo[1049:36632] returnValue: 119