iOS-合理運用設(shè)計模式-責(zé)任鏈模式-信息校驗

需求：用戶的信息錄入校驗

當(dāng)前界面的布局我是基于UIScrollview布局的，每一個單元格是UIView而不是Cell。

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看普通的實現(xiàn)方法

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假如使用了責(zé)任鏈模式

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責(zé)任鏈模式一篇很詳細(xì)的介紹。
責(zé)任鏈模式主要降低了請求發(fā)送者和接收者之間的耦合度笙什。使得多個對象都有機會處理某一個請求。在請假系統(tǒng)中可能需要多個人物對請假進行審批。采購系統(tǒng)中可能需要不同高度的人進行審批婉烟。一個請求可能由多個對象處理，但是不清楚具體接收者對象暇屋。所以將對象連成一條鏈子似袁，使請求沿著這條鏈子傳遞下去。直到被處理為止、這就是責(zé)任鏈模式昙衅。

我們?nèi)绾卧诖a中實現(xiàn)扬霜？

首先定義一個責(zé)任鏈消息

#import <Foundation/Foundation.h>
@interface ResponsibilityMessage : NSObject
@property (nonatomic, weak)   id object;//校驗對象
@property (nonatomic) BOOL       checkSuccess;//校驗成功
@property (nonatomic, strong) id errorMessage;//校驗失敗
@end

#import "ResponsibilityMessage.h"
@implementation ResponsibilityMessage
@end

其次定義一個基類鏈

#import <Foundation/Foundation.h>
#import "ResponsibilityMessage.h"
@interface ResponsibilityChain : NSObject
/**
 The object to attach.附加對象
 */
@property (nonatomic, weak) id object;
/**
 Overwrite by subclass.
 @return Can pass through or not.是否可以通過
 */
- (ResponsibilityMessage *)canPassThrough;
@end

#import "ResponsibilityChain.h"
@implementation ResponsibilityChain
- (ResponsibilityMessage *)canPassThrough {
    ResponsibilityMessage *message = [ResponsibilityMessage new];
    message.checkSuccess           = YES;
    message.object                 = self.object;
    return message;
}
@end

然后創(chuàng)建一個管理類，管理你所有的責(zé)任鏈

#import <Foundation/Foundation.h>
#import "NSObject+ResponsibilityChain.h"
@interface ResponsibilityManager : NSObject
/**
 Get all the chains.
 */
@property (nonatomic, strong, readonly) NSArray *chains;
/**
 Add chain to responsibilityManager, if the object doesn't have the value in 'responsibilityChain', it will crash.
 @param object The object that has value in 'responsibilityChain'.
 */
- (void)addChain:(NSObject *)object;
/**
 Remove chain from responsibilityManager, if the object doesn't have the value in 'responsibilityChain', it will crash.
 @param object The object that has value in 'responsibilityChain'.
 */
- (void)removeChain:(NSObject *)object;
/**
 Check all the responsibilityChains.
 @return The check message.
 */
- (ResponsibilityMessage *)checkResponsibilityChain;

#import "ResponsibilityManager.h"
@interface ResponsibilityManager ()
@property (nonatomic, strong) NSMutableArray *storeChains;
@end

@implementation ResponsibilityManager
- (instancetype)init {
    if (self = [super init]) {
        self.storeChains = [NSMutableArray array];
    }
    return self;
}

- (NSArray *)chains {
    return [NSArray arrayWithArray:self.storeChains];
}

- (void)addChain:(NSObject *)object {
    NSParameterAssert(object.responsibilityChain);
    [self.storeChains addObject:object];
}

- (void)removeChain:(NSObject *)object {
    NSParameterAssert(object.responsibilityChain);
    [self.storeChains removeObject:object];
}

- (ResponsibilityMessage *)checkResponsibilityChain {
    ResponsibilityMessage *message = nil;
    for (NSObject *chain in self.storeChains) {
        message = [chain.responsibilityChain canPassThrough];
        if (message.checkSuccess == NO) {
            break;
        }
    }
    return message;
}
@end

到這個步驟而涉，其實我們就已經(jīng)封裝成功了著瓶。
那我們?nèi)绾问褂貌拍軣o侵入性，耦合性最少呢啼县？直接上代碼

#import <Foundation/Foundation.h>
#import "ResponsibilityChain.h"
@interface NSObject (ResponsibilityChain)
@property (nonatomic, strong) ResponsibilityChain *responsibilityChain;
@end

#import "NSObject+ResponsibilityChain.h"
#import <objc/runtime.h>
@implementation NSObject (ResponsibilityChain)
- (void)setResponsibilityChain:(ResponsibilityChain *)responsibilityChain {
    responsibilityChain.object = self;
    objc_setAssociatedObject(self, @selector(responsibilityChain), responsibilityChain, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (ResponsibilityChain *)responsibilityChain {
    return objc_getAssociatedObject(self, _cmd);
}
@end

我們使用類別(分類)去給所有繼承自NSObject的對象添加責(zé)任鏈屬性材原。

針對業(yè)務(wù)我們要如何去使用呢？

封裝業(yè)務(wù)
首先具體業(yè)務(wù)具體分析季眷，使用繼承基鏈的方式余蟹，來定制我們的業(yè)務(wù)。目前我們的需求是：UITextField中文本的輸入校驗子刮。

#import "ResponsibilityChain.h"
@interface DefiningTermChain : ResponsibilityChain
+ (instancetype)DefiningTermChainWithErrorMessage:(NSString *)string;
@end

#import "DefiningTermChain.h"
#import "DJQSelectItemView.h"
#import "DJQTextFiledTitleView.h"
@interface DefiningTermChain ()
@property (nonatomic, strong) NSString *errorMessage;
@end
@implementation DefiningTermChain
- (ResponsibilityMessage *)canPassThrough {
    if ([self.object isKindOfClass:DJQSelectItemView.class]) {
        DJQSelectItemView           *selectView   = self.object;
        ResponsibilityMessage *message            = [ResponsibilityMessage new];
        message.object                            = self.object;
        message.checkSuccess                      = YES;
        if (selectView.content.length <= 0) {
            message.errorMessage = [NSString stringWithFormat:@"%@輸入不能為空", self.errorMessage];
            message.checkSuccess = NO;
        }
        return message;
    }else if ([self.object isKindOfClass:DJQTextFiledTitleView.class]){
        DJQTextFiledTitleView *titleView  = self.object;
        ResponsibilityMessage *message   = [ResponsibilityMessage new];
        message.object                   = self.object;
        message.checkSuccess             = YES;
        if ([titleView.modelDicKey isEqualToString:@"qq"]) {
            if (titleView.field.text.length < 5) {
                message.errorMessage = @"QQ號最低五位";
                message.checkSuccess = NO;
            }
        }
        if (titleView.field.text.length <= 0) {
            message.errorMessage = [NSString stringWithFormat:@"%@輸入不能為空", self.errorMessage];
            message.checkSuccess = NO;
        }
        return message;
    }else {
        UITextField           *field   = self.object;
        ResponsibilityMessage *message  = [ResponsibilityMessage new];
        message.object                  = self.object;
        message.checkSuccess           = YES;
        if (field.text.length <= 0) {
            message.errorMessage = [NSString stringWithFormat:@"%@輸入不能為空", self.errorMessage];
            message.checkSuccess = NO;
        }
        return message;
    }
}
+ (instancetype)DefiningTermChainWithErrorMessage:(NSString *)string {
    DefiningTermChain *chain = [DefiningTermChain new];
    chain.errorMessage       = string;
    return chain;
}
@end

業(yè)務(wù)模塊的使用
首先導(dǎo)入管理類和業(yè)務(wù)鏈類

//責(zé)任鏈
#import "ResponsibilityManager.h"
#import "DefiningTermChain.h"
@property (nonatomic, strong) ResponsibilityManager *responsibilityManager;
self.responsibilityManager = [ResponsibilityManager new];
//DJQTextFiledTitleView 這個類里面是包含所要顯示的信息威酒，例如校驗不通過時顯示的字段。
DJQTextFiledTitleView *fieldView    = [[DJQTextFiledTitleView alloc] initWithFrame:CGRectMake(0, y, Width, 50.f)];
fieldView.field.responsibilityChain = [DefiningTermChain DefiningTermChainWithErrorMessage:title];
        [self.responsibilityManager addChain:fieldView.field];

fieldView.textView.responsibilityChain = [DefiningTermChain DefiningTermChainWithErrorMessage:title];//title為校驗不通過的時候顯示的信息
        [self.responsibilityManager addChain:fieldView.textView];

分別是判斷是否是DJQSelectItemView,DJQTextFiledTitleView, UITextField基于不同的業(yè)務(wù)去判斷我們想要的類型挺峡。

最后我們回到校驗的地方

if (self.responsibilityManager.chains.count > 0 && [self.responsibilityManager checkResponsibilityChain].checkSuccess == NO) {
        [self djq_showToastByMessage:[self.responsibilityManager checkResponsibilityChain].errorMessage];
        return;
}

工具責(zé)任鏈github地址
備注：同事黃哥設(shè)計整理葵孤，我認(rèn)為這是很好的編程思想，所以總結(jié)加搬運和分享橱赠。
如有侵權(quán)尤仍，請告知謝謝。