iOS设计模式 - 迭代器
原理图
说明
提供一种方法顺序访问一个聚合对象中的各种元素，而又不暴露该对象的内部表示。
源码
https://github.com/YouXianMing/iOS-Design-Patterns
//
// Node.h
// IteratorPattern
//
// Created by YouXianMing on 15/10/26.
// Copyright © 2015年 YouXianMing. All rights reserved.
//
#import <Foundation/Foundation.h>
@interface Node : NSObject
/**
* 下一个节点
*/
@property (nonatomic, strong) Node *nextNode;
/**
* 节点里面的内容
*/
@property (nonatomic, strong) id item;
/**
* 初始化节点
*
* @param item 节点携带的内容
*
* @return 节点
*/
- (instancetype)initWithItem:(id)item;
@end//
// Node.m
// IteratorPattern
//
// Created by YouXianMing on 15/10/26.
// Copyright © 2015年 YouXianMing. All rights reserved.
//
#import "Node.h"
@implementation Node
- (instancetype)initWithItem:(id)item {
self = [super init];
if (self) {
self.item = item;
}
return self;
}
@end//
// LinkedList.h
// IteratorPattern
//
// Created by YouXianMing on 15/10/26.
// Copyright © 2015年 YouXianMing. All rights reserved.
//
#import <Foundation/Foundation.h>
#import "Node.h"
#import "IteratorProtocol.h"
#import "LinkedListIterator.h"
@interface LinkedList : NSObject
/**
* 头结点
*/
@property (nonatomic, strong, readonly) Node *headNode;
/**
* 节点的数目
*/
@property (nonatomic, assign, readonly) NSInteger numberOfNodes;
/**
* 添加数据
*
* @param item 数据
*/
- (void)addItem:(id)item;
/**
* 创建迭代器对象
*
* @return 迭代器对象
*/
- (id <IteratorProtocol>)createIterator;
@end//
// LinkedList.m
// IteratorPattern
//
// Created by YouXianMing on 15/10/26.
// Copyright © 2015年 YouXianMing. All rights reserved.
//
#import "LinkedList.h"
@interface LinkedList ()
/**
* 头结点
*/
@property (nonatomic, strong, readwrite) Node *headNode;
/**
* 节点的数量
*/
@property (nonatomic, assign, readwrite) NSInteger numberOfNodes;
@end
@implementation LinkedList
- (void)addItem:(id)item {
if (self.headNode == nil) {
self.headNode = [[Node alloc] initWithItem:item];
} else {
[self addItem:item node:self.headNode];
}
self.numberOfNodes++;
}
- (id <IteratorProtocol>)createIterator {
return [[LinkedListIterator alloc] initWithLinkedList:self];
}
#pragma mark - Private Methods
- (void)addItem:(id)item node:(Node *)node {
if (node.nextNode == nil) {
node.nextNode = [[Node alloc] initWithItem:item];
} else {
[self addItem:item node:node.nextNode];
}
}
@end//
// LinkedListIterator.h
// IteratorPattern
//
// Created by YouXianMing on 15/10/26.
// Copyright © 2015年 YouXianMing. All rights reserved.
//
#import <Foundation/Foundation.h>
#import "IteratorProtocol.h"
@class LinkedList;
@interface LinkedListIterator : NSObject <IteratorProtocol>
/**
* 由链表进行初始化
*
* @param linkedList 链表对象
*
* @return 迭代器工具
*/
- (id)initWithLinkedList:(LinkedList *)linkedList;
@end//
// LinkedListIterator.m
// IteratorPattern
//
// Created by YouXianMing on 15/10/26.
// Copyright © 2015年 YouXianMing. All rights reserved.
//
#import "LinkedListIterator.h"
#import "LinkedList.h"
@interface LinkedListIterator ()
@property (nonatomic, weak) LinkedList *linkedList;
@property (nonatomic, weak) Node *currentNode;
@end
@implementation LinkedListIterator
- (id)initWithLinkedList:(LinkedList *)linkedList {
if (self = [super init]) {
self.linkedList = linkedList;
self.currentNode = linkedList.headNode;
}
return self;
}
- (id)next {
id item = self.currentNode.item;
self.currentNode = self.currentNode.nextNode;
return item;
}
- (BOOL)hasNext {
if (self.currentNode == nil) {
return NO;
} else {
return YES;
}
}
- (id)item {
return self.currentNode.item;
}
@end//
// IteratorProtocol.h
// IteratorPattern
//
// Created by YouXianMing on 15/10/26.
// Copyright © 2015年 YouXianMing. All rights reserved.
//
#import <Foundation/Foundation.h>
@protocol IteratorProtocol <NSObject>
/**
* 下一个对象
*
* @return 对象
*/
- (id)next;
/**
* 是否存在下一个对象
*
* @return 对象
*/
- (BOOL)hasNext;
/**
* 内容
*
* @return 返回内容
*/
- (id)item;
@end//
// ViewController.m
// IteratorPattern
//
// Created by YouXianMing on 15/10/26.
// Copyright © 2015年 YouXianMing. All rights reserved.
//
#import "ViewController.h"
#import "LinkedList.h"
#import "LinkedListIterator.h"
@interface ViewController ()
@property (nonatomic, strong) LinkedList *linkedList;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// 创建链表结构
self.linkedList = [[LinkedList alloc] init];
// 添加链表元素
[self.linkedList addItem:@"1"];
[self.linkedList addItem:@"2"];
[self.linkedList addItem:@"3"];
[self.linkedList addItem:@"4"];
[self.linkedList addItem:@"5"];
// 创建迭代器
id <IteratorProtocol> iterator = [self.linkedList createIterator];
// 进行元素迭代
while ([iterator hasNext]) {
NSLog(@"%@", iterator.item);
[iterator next];
}
}
@end细节
