動(dòng)態(tài)命令：我們不需要新建各種命令類 （block實(shí)現(xiàn)）

DynamicComment.h

#import "TMCommandProtocol.h"
#import "TerisMachine.h"
/動(dòng)態(tài)命令
typedef void(^DynamicBlock)(TerisMachine *);
//1.實(shí)現(xiàn)命令協(xié)議
//2.傳遞接收者
@interface DynamicComment : NSObject<TMCommandProtocol>
- (instancetype)init:(TerisMachine *)tm block:(DynamicBlock)tmBlock;
+ (id<TMCommandProtocol>)createCommand:(TerisMachine *)tm block:(DynamicBlock)tmBlock;
@end

DynamicComment.h

#import "DynamicComment.h"
@interface DynamicComment()
@property (nonatomic, strong) TerisMachine *machine;
@property (nonatomic, copy) DynamicBlock tmBlock;

@end
@implementation DynamicComment

- (instancetype)init:(TerisMachine *)tm block:(DynamicBlock)tmBlock
{
    self = [super init];
    if (self) {
        self.machine = tm;
        self.tmBlock = tmBlock;
    }
    return self;
}
//關(guān)于命令方式的小框架
//創(chuàng)建對象初始化的參數(shù)過于復(fù)雜我們可以內(nèi)部提供
+ (id<TMCommandProtocol>)createCommand:(TerisMachine *)tm block:(DynamicBlock)tmBlock {
    return [[DynamicComment alloc]init:tm block:tmBlock];
}

- (void)execute {
    self.tmBlock(self.machine);
}

@end

DynamicCommentManager.h

#import <Foundation/Foundation.h>
#import "TerisMachine.h"
NS_ASSUME_NONNULL_BEGIN
//動(dòng)態(tài)命令管理器
@interface DynamicCommentManager : NSObject
- (instancetype)init:(TerisMachine *)tm ;
- (void)toLeft;
- (void)toRight;
- (void)toTransform;
- (void)undo;
- (void)undoAll;
@end

DynamicCommentManager.m

#import "DynamicCommentManager.h"
#import "DynamicComment.h"
#import "objc/message.h"

@interface DynamicCommentManager()
@property (nonatomic, strong) TerisMachine *machine;
@property (nonatomic, strong) NSMutableArray*commands;
@end

@implementation DynamicCommentManager

- (instancetype)init:(TerisMachine *)tm {
    self = [super init];
    if (self) {
        _machine = tm;
        self.commands = [NSMutableArray array];
    }
    return self;
}

- (void)toLeft {
    [self addCommand:NSStringFromSelector(_cmd)];
    if (class_respondsToSelector([self.machine class], _cmd)) {
        objc_msgSend(self.machine, _cmd);
    }//判斷類中是否包含某個(gè)方法的實(shí)現(xiàn)
  
}
- (void)toRight {
    [self addCommand:NSStringFromSelector(_cmd)];
    objc_msgSend(self.machine, _cmd);
}
- (void)toTransform {
    [self addCommand:NSStringFromSelector(_cmd)];
    objc_msgSend(self.machine, _cmd);
}

- (void)undo {
    if (self.commands.count > 0) {
        NSLog(@"撤銷");
        //撤銷
        [[self.commands lastObject]execute];
        //移除
        [self.commands removeLastObject];
    }
}

- (void)undoAll {
    NSLog(@"撤銷所有");
    //應(yīng)該倒敘刪除
    for (id <TMCommandProtocol>command in self.commands) {
        [command execute];
    }
    [self.commands removeAllObjects];
}
//根據(jù)方法名稱，動(dòng)態(tài)加載執(zhí)行對象的方法
- (void)addCommand:(NSString *)methodName {
    //獲取到方法對象
    SEL method = NSSelectorFromString(methodName);
    //添加動(dòng)態(tài)命令
    __weak DynamicCommentManager *weakSelf = self;
    [self.commands addObject:[DynamicComment createCommand:self.machine block:^(TerisMachine *tm){
        objc_msgSend(weakSelf.machine, method);
    }]];
    
}

@end

main

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // insert code here...
        NSLog(@"Hello, World!");
        TerisMachine *tm = [TerisMachine new];
        DynamicCommentManager *manager = [[DynamicCommentManager alloc]init:tm];
        [manager toLeft];
        [manager toRight];
        [manager toTransform];
//        [manager undo];
    }
    return 0;
}

來自潭州課堂