这几天一直在进行知乎日报的仿写，仿写过程中积累了许多实用的开发经验，并对MVC有了更深的了解，特撰此篇作以总结

---

---

第一周

将网络请求封装在一个单例类Manager中

由于知乎日报所请求的API较多，若将网络请求三板斧直接写在Controller中会代码十分冗杂，干脆直接将AFNetWorking和JSONModel封装到一个全局的Manager单例类中，在Manager类中进行网络请求和数据解析，不同的API写成不同的方法，具体实现看这篇博客（）

typedef void(^LatestStoriesBlock)(LatestStoriesModel* latestStoriesModel);
typedef void(^BeforeStoriesModelBlock)(StoriesModel* beforeStoriesModel);
typedef void(^StoriesContentBlock)(StoriesContentModel* storiesContentModel);
typedef void(^StoriesExtraContentBlock)(StoriesExtraContentModel* storiesExtraContentModel);
typedef void(^ErrorBlock)(NSError* error);@interface Manager : NSObject//单例实例
+ (instancetype)sharedManager;//请求最新消息
- (void)requestTopStoriesData: (LatestStoriesBlock)success failure: (ErrorBlock)failure;//缓存网络图片
+ (void)setImage: (id)imageView WithString: (NSString *)string;//请求指定日期的消息内容
- (void)requestBeforeDate: (NSString *)date beforeStoriesData: (BeforeStoriesModelBlock)success failure: (ErrorBlock)failure;//加载Web网页在WebView中
- (void)setWebView: (WKWebView *)webView WithString: (NSString *)string;//请求指定网页的内容（主要为了获取share_url）
- (void)requestWebContentWithID: (NSString *)string StoriesContentData: (StoriesContentBlock)success failure: (ErrorBlock)failure;//请求制定网页的额外内容
- (void)requestExtraContentWithID: (NSString *)string StoriesExtraContentData: (StoriesExtraContentBlock)success failure: (ErrorBlock)failure;@end

解析下来的数据用Block传值（【iOS】属性传值、代理传值（委托）、通知传值、KVO传值、Block传值、单例传值）的方式在Controller中接收

SDWebImage库的简单使用

使用WebImage库主要是为了缓存网络图片并加载在UIImageView上，只需在loadRequest:方法中传入指定的NSURL

+ (void)setImage:(UIImageView *)imageView WithString:(NSString *)string {string = [string stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];NSURL* url = [NSURL URLWithString:string];[imageView sd_setImageWithURL: url placeholderImage: [UIImage imageNamed: @"placeholder.png"]];
}

运用时间戳处理当前时间

时间戳是指格林威治时间1970年01月01日00时00分00秒（北京时间1970年01月01日08时00分00秒）起至现在的总秒数。

处理方法单独写在一个工具类中方便管理

@interface DateModel : NSObject+ (NSTimeInterval)getTimestampWithTimeString: (NSString *)timeString;
+ (NSString *)getMonthWithTimeString: (NSString *)timeString;
+ (NSString *)getDayWithTimeString: (NSString *)timeString;
+ (NSString *)getDateWithTimeString: (NSString *)timeString;
+ (NSString *)getBeforeDateWithTimeString: (NSString *)timeString;@end

获取时间戳方法

//传入时间格式：20230917
+ (NSTimeInterval)getTimestampWithTimeString: (NSString *)timeString {NSDateFormatter* dateFormatter = [[NSDateFormatter alloc] init];[dateFormatter setDateFormat: @"YYYYMMdd"];NSDate* date = [dateFormatter dateFromString: timeString];NSTimeInterval timeStamp = [date timeIntervalSince1970];return timeStamp;
}

通过时间戳处理指定时间

    NSDateFormatter* dateFormatter = [[NSDateFormatter alloc] init];//YYYY获取年份 MM获取月份 dd获取日份 //当然也可以混用，如：@"MM月dd日"，这样就会得到一个指定格式的时间字符串[dateFormatter setDateFormat: @"MM"];NSTimeInterval timeStamp = [self getTimestampWithTimeString: timeString];NSDate* date = [NSDate dateWithTimeIntervalSince1970: timeStamp];NSString* string = [dateFormatter stringFromDate: date];

自定义NavigationBar

在push页面过程中，使用系统的NavigationBar会发现UI是逐渐消失的，而知乎日报App是第二个页面直接覆盖过去的，想不到什么实现这种效果的巧妙方法，这里我直接在NavigationBar的位置直接粘上一个UIView，并在当前控制器隐藏NavigationBar

- (void)viewWillAppear:(BOOL)animated {[self.navigationController setNavigationBarHidden: YES animated: YES];
}- (void)viewWillDisappear:(BOOL)animated {[self.navigationController setNavigationBarHidden: NO animated: YES];
}

这两个方法涉及UIViewController的生命周期【iOS】ViewController生命周期

---

第二周

在UITableView的section之间的headerView上画UI

tableView提供了这样一个协议方法自定义section

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {if (section > 1) {UIView* view = [[UIView alloc] init];UILabel* dateLabel = [[UILabel alloc] init];dateLabel.textColor = [UIColor grayColor];dateLabel.font = [UIFont boldSystemFontOfSize: 15];dateLabel.text = [DateModel getDateWithTimeString: self.beforeDateArray[section - 1]];[view addSubview: dateLabel];UIView* grayView = [[UIView alloc] init];grayView.backgroundColor = [UIColor colorWithRed: 231.0 / 255 green: 231.0 / 255 blue: 231.0 / 255 alpha: 1];[view addSubview: grayView];[dateLabel makeConstraints:^(MASConstraintMaker *make) {make.left.equalTo(view.left).offset(MINIGAP);make.centerY.equalTo(view.centerY);}];[grayView makeConstraints:^(MASConstraintMaker *make) {make.height.equalTo(1);make.left.equalTo(dateLabel.right).offset(MINIGAP);make.right.equalTo(view.right);make.centerY.equalTo(view.centerY);}];return view;} else {return nil;}
}

但section之间的距离跟返回view的高度是没有关系的，要想消除分区之间的留白，给以下属性赋值即可

 self.tableView.sectionHeaderTopPadding = 0;

WKWebView的使用

只需传入NSRequest即可在webView上加载web网页

- (void)setWebView:(WKWebView *)webView WithString:(NSString *)string {//NSLog(@"%@", string);NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString: string]];[webView loadRequest: request];
}

WKWebView网页加载不出来

大概查了一下

出现加载不出来本质原因是，如果没在plist文件中设置App Transport Security Settings的话，加载https链接，肯定是加载不出来的，第一次加载不出来，产生了缓存，第二次再去加载也加载不出来了，可以尝试一下就知道了

线程问题

网络请求是在Controller中调用的，请求下来的数据会赋值给View的各种属性，但请求是需要时间的，如果在viewDidLoad里面先初始化view，那么还没等数据请求下来，UI就已经布局，那么只会显示空白的UI控件，未解决这一问题，用到了GCD的一个方法：

        dispatch_async(dispatch_get_main_queue(), ^{[self sendViewStories: latestStoriesModel];[self createTopImages];[self setViewAndModel];[self requestBeforeStoriesWithDate: self.latestStoriesModel.date];});

---

第三周

attempting to add unsupported attribute: (null)错误

使用masonry，设置约束时，约束冲突或约束不全

解决方法就是补充必要的约束或者调整调用顺序

FMDB数据库的简单使用

FMDB库将C语言风格的MySqlite数据库封装成了OC风格的方法，而且操作比C语言文件操作更容易

以点赞集合（存储相应网页的ID）为例，实现了数据库的增删改查：

#pragma mark 点赞操作
- (void)createStoriesLikeSet {NSString* doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];NSString* fileName = [doc stringByAppendingPathComponent: @"likeDatabase.sqlite"];NSLog(@"%@", fileName);self.likeDatabase = [FMDatabase databaseWithPath: fileName];if ([self.likeDatabase open]) {BOOL result = [self.likeDatabase executeUpdate: @"CREATE TABLE IF NOT EXISTS likeDatabase (idLabel text NOT NULL)"];if (result) {FMResultSet* resultSet = [self.likeDatabase executeQuery: @"SELECT * FROM likeDatabase"];while([resultSet next]) {[self.storiesLikeSet addObject:[resultSet stringForColumn: @"idLabel"]];}NSLog(@"create table succeed");} else {NSLog(@"fail to open database");}[self.likeDatabase close];}
}- (void)saveStoriesLikeSet {if ([self.likeDatabase open]) {for (NSString* ID in self.storiesLikeSet) {FMResultSet* resultSet = [self.likeDatabase executeQuery: @"SELECT * FROM likeDatabase WHERE idLabel = ?", ID];if (![resultSet next]) {BOOL result = [self.likeDatabase executeUpdate: @"INSERT INTO likeDatabase (idLabel) VALUES (?)", ID];if (result) {NSLog(@"insert table succeed");} else {NSLog(@"insert table error");}}}[self.likeDatabase close];}
}- (void)deleteLikeSetWithID:(NSString*)ID {if ([self.likeDatabase open]) {BOOL result = [self.likeDatabase executeUpdate: @"delete from likeDatabase WHERE idLabel = ?", ID];if (result) {NSLog(@"delete table succeed");} else {NSLog(@"delete table error");}[self.likeDatabase close];}
}

WebView界面无限右滑

向右加载新一天的消息时，主页的tableViewCell也要更新，这里使用了通知中心进行消息传递

    if (self.scrollView.contentOffset.x == Screen_WIDTH * self.numberOfStories) {[[NSNotificationCenter defaultCenter] postNotificationName: @"upDateRight" object: nil];return;}

滑到了新增加的画布时，先通知首页更新一天数据：

//更新首页
[[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(upDateRight) name: @"upDateRight" object: nil];- (void) upDateRight {StoriesModel* storiesModel = [self.beforeStoriesModelArray lastObject];NSString* beforeDate = storiesModel.date;[self requestBeforeStoriesWithDate: beforeDate];
}

然后将更新后的数据传回WebView相关页面，加载新的Web

- (void)requestBeforeStoriesWithDate: (NSString *)date {[self.manager requestBeforeDate: date beforeStoriesData:^(StoriesModel * _Nonnull beforeStoriesModel) {if (!self.beforeStoriesModelArray) {self.beforeStoriesModelArray = [[NSMutableArray alloc] init];}[self.beforeStoriesModelArray addObject: beforeStoriesModel];//NSLog(@"%@", beforeStoriesModel.date);dispatch_async(dispatch_get_main_queue(), ^{[self sendViewStories: beforeStoriesModel];self.mainView.isLoading = NO;[self.mainView.tableView reloadData];NSMutableArray* storiesArray = [[NSMutableArray alloc] init];for (Stories* stories in beforeStoriesModel.stories) {[storiesArray addObject: stories.id];}[[NSNotificationCenter defaultCenter] postNotificationName: @"upDateRight-Two" object:nil userInfo: @{@"value" : storiesArray}];});} failure:^(NSError * _Nonnull error) {NSLog(@"请求过往消息失败");}];
}

但这里面遇到了数组越界问题，向右滑着滑着就访问到了不存在的索引，目前尚未解决

源码

Github DEMO

这里先挂一个半成品，之后会想办法解决这个bug，并尝试实现评论区、收藏夹和夜间模式等。