1.removeItemAtURL删除本地文件document。
2。创建子目录来存储文件。

    self.ubiquityURL = [[fMgr URLForUbiquityContainerIdentifier:nil] URLByAppendingPathComponent:@"Documents"];

3。创建文档使用self.ubiquityURL目录
4。在iCloud中使用set谓词document.doc搜索：[NSpredicate predicateWithFormat：@“％K like 'document.doc'”，NSMetadataItemFSNameKey];

NSMetaDataItemFSSizeKey, NSMetaDataItemFSCreationDataKey, NSMetaDataItemFSContentChangeDataKey

5.Then设置搜索范围NSMetaDataQueryUbiquitysDocumentsScope的;

  [self.metaDataQuery setSearchScopes:[NSArray arrayWithObject:NSMetadataQueryUbiquitousDocumentsScope]];

PS：另外一个搜索数据：NSMetaDataQueryUbiquitysDataScope另一个范围;
6。开始查询[self.metaDataQuery startQuery];
7。设置一个通知，当搜索查询完成：NSMetaDataQueryDidfinishGatheringNotification

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(metaDataQueryDidFinishGathering:) name:NSMetadataQueryDidFinishGatheringNotification object:self.metaDataQuery];

8.用metaDataQueryDidfinishGather继续
a. NSMetadataQuery *query = [notificaiton object];
b.在查询中停止通知 remove the notification from query;
c。停止查询; stop query;

9。得到的结果对象从[查询结果] got the result object from [query result]

        NSArray *results = [[NSArray alloc] initWithArray:[query results] ];

10. check if the [result count] == 1. if yes, got the ubiquityURL and document.doc using:
The important thing is if there’s only search a specific file, then the first file is what we need.

self.ubiquityURL = [result[0] valueForAttribute:NSMetaDataItemURLKey];
           self.document = [[BKDocument alloc] initWithFileURL:self.ubiquityURL];
[self.document openWithCompletionHandler:^(BOOL success) {
            if (success) {
                self.textView.text = self.document.userText;
            }else{
                NSLog(@"Faild to open");
            }
        }]

11.if there’s not any result, then create it using saveToURL:
UIDocumentSaveForOverWriting,UIDocumentSaveForCreating
12. Finally Click the Save button to save text to document;

//
//  BKViewController.h
//  BKDocument
//
//  Created by xushao on 13-4-5.
//  Copyright (c) 2013年 xushao. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "BKDocument.h"

@interface BKViewController : UIViewController
@property(nonatomic, strong)BKDocument *document;
@property(nonatomic, strong) NSURL *documentURL;

@property(nonatomic, strong)NSMetadataQuery *metaDataQuery;

@property(nonatomic, strong)NSURL *ubiquityURL;
@property (strong, nonatomic) IBOutlet UITextView *textView;

- (IBAction)savebutton:(id)sender;

@end

//
//  BKViewController.m
//  BKDocument
//
//  Created by xushao on 13-4-5.
//  Copyright (c) 2013年 xushao. All rights reserved.
//

#import "BKViewController.h"

@interface BKViewController ()

@end

@implementation BKViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSArray *filePath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    NSString *dataPath = filePath[0];

    NSString *path = [[NSString alloc] stringByAppendingPathComponent:dataPath];

    NSFileManager *fMgr = [NSFileManager defaultManager];
    NSError *error;
    [fMgr removeItemAtPath:path error:&error];

    self.ubiquityURL = [[fMgr URLForUbiquityContainerIdentifier:nil] URLByAppendingPathComponent:@"Documents"];

    if ([fMgr fileExistsAtPath:[self.ubiquityURL path]]==NO) {
        [fMgr createDirectoryAtURL:self.ubiquityURL withIntermediateDirectories:YES attributes:nil error:nil];
    }
    self.ubiquityURL = [self.ubiquityURL URLByAppendingPathComponent:@"document.doc"];

        self.metaDataQuery = [[NSMetadataQuery alloc] init];

    [self.metaDataQuery setPredicate:[NSPredicate predicateWithFormat:@"%K like 'document.doc'",NSMetadataItemFSNameKey]];
    [self.metaDataQuery setSearchScopes:[NSArray arrayWithObject:NSMetadataQueryUbiquitousDocumentsScope]];
    [self.metaDataQuery startQuery];

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(metaDataQueryDidFinishGathering:) name:NSMetadataQueryDidFinishGatheringNotification object:self.metaDataQuery];
	// Do any additional setup after loading the view, typically from a nib.

}

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

                        -(void)metaDataQueryDidFinishGathering:(NSNotification *)notificaiton
    {
        NSMetadataQuery *query = [notificaiton object];
        [[NSNotificationCenter defaultCenter] removeObserver:self name:NSMetadataQueryDidFinishGatheringNotification object:query];

        [query stopQuery];

        NSArray *results = [[NSArray alloc] initWithArray:[query results] ];
        if ([results count]==1) {
            self.ubiquityURL = [results[0] valueForAttribute:NSMetadataItemURLKey];

            self.document = [[BKDocument alloc] initWithFileURL:self.ubiquityURL];
        [self.document openWithCompletionHandler:^(BOOL success) {
            if (success) {
                self.textView.text = self.document.userText;
            }else{
                NSLog(@"Faild to open");
            }
        }];
        }else{
            self.document = [[BKDocument alloc] init];

            [self.document saveToURL:self.ubiquityURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
                if (success) {
                    NSLog(@"Create Success");
                }else{
                    NSLog(@"Couldn't create file");
                }
            }];

        }

                        }
- (IBAction)savebutton:(id)sender {

    self.document.userText = self.textView.text;

    [self.document saveToURL:self.ubiquityURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:^(BOOL success) {
        if (success) {
            NSLog(@"Over writing success");
        }else{
            NSLog(@"Over writing failed");
        }
    }];
}
@end