iOS 学习

前提是已经知道了有哪些 key 值

Model 类：

.h

@interface ListModel : NSObject

@property (nonatomic, copy)NSString *time;
@property (nonatomic, copy)NSString *cname;
@property (nonatomic, copy)NSString *summary;
@property (nonatomic, copy)NSString *title;
@property (nonatomic, copy)NSString *type;

- (void)createArray:(NSDictionary *)result
         dataSource:(NSMutableArray *)dataSource;

 .m

- (void)createArray:(NSDictionary *)result
         dataSource:(NSMutableArray *)dataSource
{
    UserModel *userModel = [[UserModel alloc]init];
    NSArray *array = result[@"news"];
    for (NSDictionary *dict in array) {
        ListModel *listModel = [[ListModel alloc]init];
        listModel.cname      = [NSString stringWithFormat:@"%@",dict[@"cname"]];
        listModel.summary    = [NSString stringWithFormat:@"%@",dict[@"summary"]];
        listModel.title      = [NSString stringWithFormat:@"%@",dict[@"title"]];
        listModel.type       = [NSString stringWithFormat:@"%@",dict[@"type"]];
        listModel.time       = [NSString stringWithFormat:@"%@",dict[@"lastUpdateTime"]];
        [dataSource addObject:listModel];
        //NSLog(@"cname:%@",listModel.type);
        
        //时间戳转换为时间
        NSDate *startDate = [NSDate dateWithTimeIntervalSince1970:[listModel.time integerValue]];
        NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
        [formatter setDateFormat:@"yy-MM-dd"];
        NSString *beginStr = [formatter stringFromDate:startDate];
        listModel.time = beginStr;
        if (!([userModel selectTable].count > 5)) {
            [userModel insert:listModel];
        }
    }
}

FMDB: 

- (BOOL)delteSqlite {
    if ([self isSqliteExist]) {
        NSString *path = [NSTemporaryDirectory()stringByAppendingString:@"user.db"];
        NSFileManager *manager = [NSFileManager defaultManager];
        NSError *error;
        [manager removeItemAtPath:path error:&error];
        if (error) {
            NSLog(@"delete sqlite failed");
        }else{
            NSLog(@"delete sqlite success");
        }
        return YES;
    }else{
        NSLog(@"sqlite isn't exist");
        return NO;
    }
    return NO;
}

#pragma mark - 检测本地文件是否存在
- (BOOL)isSqliteExist {
    NSString *path = [NSTemporaryDirectory()stringByAppendingString:@"user.db"];
    NSFileManager *manager = [NSFileManager defaultManager];
    if ([manager fileExistsAtPath:path]) {
        NSLog(@"sqlite is exist");
        return YES;
    }else{
        NSLog(@"sqlite isn't exist, prepare to create");
        return NO;
    }
}

#pragma mark -- 建数据库
- (void)openDB {
    NSString *path = [NSTemporaryDirectory()stringByAppendingString:@"user.db"];
    NSLog(@"path:%@",path);
    _db = [FMDatabase databaseWithPath:path];
    if ([_db open]) {
        //建表
        BOOL result = [_db executeUpdate:@"CREATE TABLE IF NOT EXISTS NewsInfo(id integer PRIMARY KEY AUTOINCREMENT,cname text NOT NULL,summary text NOT NULL,title text NOT NULL,type text NOT NULL,time text NOT NULL)"];
        if (result) {
            NSLog(@"create table success");
        }else{
            NSLog(@"create tabble success");
            [_db close];
        }
    }else{
        [_db close];
        NSLog(@"open db failed");
    }
}

#pragma mark - 查询数据库
- (NSMutableArray *)selectTable
{
    if (![_db open]) {
        [self openDB];
    }
    NSMutableArray *tempArray = [NSMutableArray array];
    if ([_db open]) {
        FMResultSet *resultSet = [_db executeQuery:@"select *from NewsInfo;"];
        while ([resultSet next]) {
            ListModel *listModel = [[ListModel alloc]init];
            listModel.cname   = [resultSet objectForColumnName:@"cname"];
            listModel.summary = [resultSet objectForColumnName:@"summary"];
            listModel.title   = [resultSet objectForColumnName:@"title"];
            listModel.type    = [resultSet objectForColumnName:@"type"];
            listModel.time    = [resultSet objectForColumnName:@"time"];
            [tempArray addObject:listModel];
        }
        [_db close];
    }
    return tempArray;
}

#pragma mark - 插入进表
- (void)insert:(ListModel *)model
{
    if (![_db open]) {
        [self openDB];
    }
    [_db executeUpdate:@"INSERT INTO NewsInfo(cname,summary,title,type,time)VALUES(?,?,?,?,?)",model.cname,model.summary,model.title,model.type,model.time];
}

#pragma mark - 修改某个值
- (void)update:(NSString *)value to:(NSString *)key {
    if (![_db open]) {
        [self openDB];
    }
    if ([_db open]) {
        NSString *updateSql = [NSString stringWithFormat:@"update NewsInfo set %@='%@'",key,value];
        BOOL res = [_db executeUpdate:updateSql];
        
        if (!res) {
            NSLog(@"error when insert db table");
        } else {
            NSLog(@"success to insert db table");
        }
        [_db close];
    }
}

VC：

- (void)viewDidLoad {
    [super viewDidLoad];
    [self addBtn];
    
    self.title = @"新闻";
    _userModel = [[UserModel alloc]init];
    _dataSource = [[NSMutableArray alloc]initWithCapacity:5];
    [self.view addSubview:self.tableView];

    [self isRequestData];
}

#pragma mark - 添加一个删除数据库的按钮
- (void)addBtn {
    UIBarButtonItem *item = [[UIBarButtonItem alloc]initWithTitle:@"delete" style:UIBarButtonItemStylePlain target:self action:@selector(deleteSqlite)];
    self.navigationItem.rightBarButtonItem = item;
}

#pragma mark 删除数据库按钮方法
- (void)deleteSqlite {
    [_userModel delteSqlite];
}

#pragma mark - 本地数据库有值就不请求数据,取本地数据库值
- (void)isRequestData {
    if ([_userModel isSqliteExist]) {
        _dataSource = [_userModel selectTable];
        dispatch_async(dispatch_get_main_queue(), ^{
            [_tableView reloadData];
        });
    }else{
        //创建一个异步队列解析 json，防止阻塞主线程
        dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);
        dispatch_async(queue, ^{
            [self urlStr];
        });
    }
}

#pragma mark -- 解析 JSON
- (void)urlStr
{
    NSURL *url = [NSURL URLWithString:URLSTR];
    NSURLSession *session = [NSURLSession sharedSession];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        
        NSError *error1;
        //解析 json，返回字典，这里解析出来是 unicode 编码，不影响正常显示
        NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error1];
        
        ListModel *listModel = [[ListModel alloc]init];
        [listModel createArray:dict dataSource:_dataSource];
        
        //数据源开始是空的，因为网络等原因...等数据源有值了，在主线程刷新 TabelView
        dispatch_async(dispatch_get_main_queue(), ^{
            [_tableView reloadData];
        });
    }];
    [task resume];
}

#pragma mark -- UITableViewDataSource
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return _dataSource.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    
    static NSString *cell_id = @"cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cell_id];
    if (!cell) {
        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cell_id];
    }
    ListModel *listModel = _dataSource[indexPath.row];
    cell.textLabel.text = listModel.title;
    cell.detailTextLabel.text = listModel.time;
    return cell;
}

#pragma mark -- UITableViewDelegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    
    ListModel *listModel = _dataSource[indexPath.row];
    DetailViewController *detailVC = [[DetailViewController alloc]init];
    [self.navigationController pushViewController:detailVC animated:YES];
    detailVC.titleStr = listModel.cname;
    detailVC.contentStr = listModel.summary;
}

#pragma mark -- getter
- (UITableView *)tableView {
    if (!_tableView) {
        _tableView = [[UITableView alloc]initWithFrame:self.view.frame];
        _tableView.delegate = self;
        _tableView.dataSource = self;
    }
    return _tableView;
}

完整代码，见 github