云端iclound使用-陈棚

使用NSmetadataQuery查询文档,增加,删除,编辑

界面设计完成后效果如图:

程序清单:FKDiary.h

@interface FKDiary : UIDocument

@property (nonatomic,strong) NSData         *diaryData;
@property (nonatomic,copy) NSString       *fileURL;
@end

程序清单FKDiary.m

#import "FKDiary.h"

@implementation FKDiary

//保存该对象时自动调用该方法
-(id)contentsForType:(NSString *)typeName error:(NSError *__autoreleasing *)outError
{
    NSLog(@"保存文件到URl %@!",self.fileURL);
    if (self.diaryData == nil) {
        return  [[NSData alloc]init];
        
    }
    //将diaryData作为放回值,程序将会把该返回值保存到云端
    return [self.diaryData copy];
}
//读取该对象时自动调用该方法
-(BOOL)loadFromContents:(id)contents ofType:(NSString *)typeName error:(NSError *__autoreleasing *)outError
{
    NSLog(@"从云端下载的数据为:%@",contents);
    //将从云端下载得到的数据赋给diaryData数据
    self.diaryData = [contents mutableCopy];
    return true;
}

程序清单:FKMasterController.m

#import "FKDiary.h"

#import "ViewController.h"
@interface FKMasterController ()<UIAlertViewDelegate>
{
    //定义导航栏左边的按钮
    UIBarButtonItem *deleteButton;
}
@property (strong,nonatomic)NSMetadataQuery      *query;
@property (strong,nonatomic)NSMutableArray       *documentFilenames;
@property (strong,nonatomic)NSMutableArray       *documentURLs;
@property (strong,nonatomic)FKDiary              *chosenDiary;

@end

@implementation FKMasterController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //创建导航栏邮编的按钮
    UIBarButtonItem *addButton = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(addDiary)];
    //将导航栏按钮设置为导航栏的右边按钮
    self.navigationItem.rightBarButtonItem = addButton;
    //创建导航栏左边的按钮
    deleteButton = [[UIBarButtonItem alloc]initWithTitle:@"删除" style:UIBarButtonItemStylePlain target:self action:@selector(deleteDiary)];
    //创建导航栏左边的按niu
    self.navigationItem.leftBarButtonItem = deleteButton;
    //调用reloadFiles从云端下载文件
    [self reloadFiles];
}
-(void)addDiary
{
    //使用UIAlertView来获取文件名字
    UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"输入日记名" message:@"输入日记名称" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"创建", nil];
    //设置该UIAlertView的风格为带输入框的UIAlertView
    alert.alertViewStyle = UIAlertViewStylePlainTextInput;
    [alert show];
    
}

-(NSURL *)urlForFilename:(NSString *)filename
{
    //获取默认的NSFileManager对象
    NSFileManager *fileManager = [NSFileManager defaultManager];
    //根据Identifier获取系统的Ubiquity Container
    //如果传入nil参数,则默认获取第一个Ubiquity Container
    NSURL *baseURL = [fileManager URLForUbiquityContainerIdentifier:nil];
    //获取云端Ubiquity Container的Documents子目录
    NSURL *pathURL = [baseURL URLByAppendingPathComponent:@"Documents"];
    //在Documents子目录下添加文件名,作为保存文件的URL
    NSURL *destinationURL = [pathURL URLByAppendingPathComponent:filename];
    return  destinationURL;
}

-(void)reloadFiles
{
    //创建一个NSMetataQuery对象
    self.query = [[NSMetadataQuery alloc]init];
    //设置查询谓词
    self.query.predicate = [NSPredicate predicateWithFormat:@"%K like '*.diary'",NSMetadataItemFSNameKey];
    //设置查询范围,此处指定查询范围为NSMetadataQueryUbiquitousDocumentsScope
//    即在云端的Documents目录下查询
    self.query.searchScopes = [NSArray arrayWithObject:NSMetadataQueryUbiquitousDataScope];
    //获取数据结束时激发updateUbiquitousDocuments方法
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(updateUbiquitousDocuments:) name:NSMetadataQueryDidFinishGatheringNotification object:nil];
    //查询更新完成时激发updateUbiquitousDocuments方法
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(updateUbiquitousDocuments:) name:NSMetadataQueryDidUpdateNotification object:nil];
    
    //开始查询
    [self.query startQuery];
}


-(void)updateUbiquitousDocuments:(NSNotification *)notification
{
    self.documentURLs = [NSMutableArray array];
    self.documentFilenames = [NSMutableArray array];
    //对查询结果进行排序,排序所使用的比较标准是创建时间
    NSArray *results = [self.query.results sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        NSMetadataItem *item1 = obj1;
        NSMetadataItem *item2 = obj2;
        //比较两个NSMetadataItem的时间
        return  [[item2 valueForAttribute:NSMetadataItemFSCreationDateKey] compare:[item1 valueForAttribute:NSMetadataItemFSCreationDateKey]];
    }];
    //遍历查询结果
    for (NSMetadataItem *item in results) {
        //查询结果中包含的NSURL属性
        NSURL *url = [item valueForAttribute: NSMetadataItemURLKey];
        //将NSURL添加到documentURLs集合中
        [self.documentURLs addObject:url];
        //将NSURL的最后一个路径(文件名)添加到documentfilenames集合中
        [self.documentFilenames addObject:url];
        
    }
    //控制界面上表哥重新加载数据
    [self.tableView reloadData];
    
}
-(void)perpareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    //如果sender等于self,则表明是新建FKDiary后导航到查看,编辑日记的视图空孩子气
    if (sender == self) {
        UIViewController *destination = segue.destinationViewController;
        //将用户新建的FKDiary对象传给目标视图控制器
        if ([destination respondsToSelector:@selector(setDetailItem:)])
        {
            [destination setValue:self.chosenDiary forKey:@"detailItem"];
        }
    }else
    {
        //获取激发视图切换的单元格所在的NSIndexPath
        NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
        //获取激发视图切换的单元格中显示的文件名
        NSString *filename = [self.documentFilenames objectAtIndex:indexPath.row];
        //获取该文件名对应的FKDiary的存储URL
        NSURL *docURl = [self urlForFilename:filename];
        //以指定的docUrl创建FKDiary对象
        self.chosenDiary = [[FKDiary alloc]initWithFileURL:docURl];
        //读取chosenDiary文档
        [self.chosenDiary openWithCompletionHandler:^(BOOL success) {
           //如果读取成功
            if (success) {
                ViewController *destination = (ViewController *)segue.destinationViewController;
                //将读取成功的chosenDiary传给destination
                destination.detailItem = self.chosenDiary;
                //调用destination的changeDisplay更新显示
                [destination changeDisplay];
            }
            else
            {
                NSLog(@"failed to load!");
            }
        }];
    }
}
-(void)deleteDiary
{
    //使用动画切换表格的编辑状态
    [self.tableView setEditing: !self.tableView.editing animated:YES];
    //修改deleteButton按钮的文本
    deleteButton.title = [deleteButton.title isEqualToString:@"删除"]?@"完成":@"删除";
    
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    return [self.documentFilenames count];
}

#pragma mark - UIAlertViewDelegate
-(void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 1) {
        //获取用户zaiUIAlerView中输入的文件名,并添加.diary扩展名
        NSString *filename = [NSString stringWithFormat:@"%@.diary",[alertView textFieldAtIndex:0].text];
        //获取云端文档存储的url
        NSURL *saveURL = [self urlForFilename:filename];
        //创建一个fKDiary (UIDocument的子类)对象
        self.chosenDiary = [[FKDiary alloc]initWithFileURL:saveURL];
        //保存chosenDiary文档
        [self.chosenDiary saveToURL:saveURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
            if(success)
            {
                NSLog(@"保存成功");
                [self reloadFiles];
                //执行masterTodetail segue,导航到查看,编辑日记的视图控制器
                [self performSegueWithIdentifier:@"masterToDetail" sender:self];
                
            }else
            {
                NSLog(@"保存失败");
            }
        }];
    }
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cellID" forIndexPath:indexPath];
    //根据单元格所在的行号获取对应的文档名
    NSString *path = [self.documentFilenames objectAtIndex:indexPath.row];
    //设置该单元格的文本为文档名取消后缀
    cell.textLabel.text = path.lastPathComponent.stringByDeletingPathExtension;
    // Configure the cell...
    
    return cell;
}
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath
{
    //返回UITableViewCellEditingStyleDeleter代表删除
    return UITableViewCellEditingStyleDelete;
}

/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
    // Return NO if you do not want the specified item to be editable.
    return YES;
}
*/


// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        //获取用户视图删除的行号
        NSInteger rowNo = [indexPath row];
        //调用NSfileMangaer的removeItemAtURL:error:方法即可删除云端文档
        [[NSFileManager defaultManager]removeItemAtURL:[self.documentURLs objectAtIndex:rowNo] error:nil];
        //从底层NSArray集合中删除指定数据项
        [self.documentFilenames removeObjectAtIndex:rowNo];
        //从UITableView程序界面删删除指定表格行
        [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
        
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
    } else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }   
}