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 ()
{
//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
  }
  }