PS:今天上午，非常郁闷，有很多简略基础的问题搞得我有些迷茫，哎，代码几天不写就忘。目前又不当COO，还是得用心记代码哦！
一、文件操作
2、 相干方法：
# 使用 NSSearchPathForDiretoriesInDomains() 方法只能定位 Caches 目录和 Documents 目录
NSArray *paths = NSSearchPathForDiretoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)
# NSHomeDirectory(); 可以取得应用的根目录
e.g 通过 home 取 tmp 目录
NSString *fileName = [NSHomeDirectory() stringByAppendingPathComponent:@"tmp/myFile.txt"];
# 使用资源文件：
# 应用安装到设备上后，资源文件是在 app（即home目录） 目录下的
e.g 获取资源文件
NSString *filePath = [[NSBundle mainBundle] pathForResourcce:@"f" ofType:@"txt"];
NSStirng *fileContent = [[NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error nil];
;
* 1 、 sqlite3 *db, 数据库句柄，跟文件句柄 FILE 很相似
* 2 、 sqlite3_stmt *stmt ，这个相当于 ODBC 的 Command 对象，用于保存编译好的 SQL 语句
* 3 、 sqlite3_open() 打开数据库，没有数据库时创建
* 4 、 sqlite3_exec() 执行非查询的 sql 语句
* 5 、 Sqlite3_step() 在调用 sqlite3_prepare 后，使用这个函数在记录集中移动
* 6 、 sqlite3_close() 关闭数据库
*
* 还有一系列用于从记录集字段中获取数据， e.g
* 1 、 sqlite3_column_text() 取 text 类型的数据
* 2 、 sqlite3_column_blob() 取 blob 类型数据
* 3 、 sqlite3_column_int() 取 int 类型数据
* 数据库操作要添加 libsqlite3.dylib 静态库
* 包含头文件 ： import "sqlite3.h"
*/
- ( void )parser:( NSXMLParser *)parser didStartElement:( NSString *)elementName namespaceURI:( NSString *)namespaceURI qualifiedName:( NSString *)qName attributes:( NSDictionary *)attributeDict；
//
剖析完一个元素时回调的方法
/* { "aps": { "alert" : { "body" : "a msg come!" }, "bage": 3, "sound" : "def.mp3" } } */ NSString *strJson = @"{\"aps\":{\"alert\":{\"body\":\"a msg come!\"}, \"bage\":3, \"sound\":\"def.mp3\"}}"; // result中即为剖析出来的json文件，通过valueForKey便可读到相应的数据 NSDictionary *result = [strJson objectFromJSONString]; NSLog(@"%@", result); NSString *myJsonPath = [[NSBundlemainBundle] pathForResource:@"my"ofType:@"json"]; NSString *myJsonStr = [NSStringstringWithContentsOfFile:myJsonPath encoding:NSUTF8StringEncodingerror:nil]; NSLog(@"myJsonStr : %@", myJsonStr); NSDictionary *myResult = [myJsonStr objectFromJSONString]; NSLog(@"myJson : %@", myResult); // 生成json文件 NSMutableDictionary *jsonDic = [[NSMutableDictionarydictionary] autorelease]; NSMutableDictionary *alert = [[NSMutableDictionarydictionary] autorelease]; NSMutableDictionary *aps = [[NSMutableDictionarydictionary] autorelease]; [alert setObject:@"a msg come!"forKey:@"body"]; [aps setObject:alert forKey:@"alert"]; [aps setObject:@"3"forKey:@"bage"]; [aps setObject:@"def.mp3"forKey:@"sound"]; [jsonDic setObject:aps forKey:@"aps"]; NSString *jsonStr = [jsonDic JSONString];
@property
(
nonatomic
,
retain
,
readonly
)
NSManagedObjectModel
*managedObjectModel;
@property
(
nonatomic
,
retain
,
readonly
)
NSPersistentStoreCoordinator
*persisteneStoreCoordinator;
- (
void
)saveContext;
- (
NSURL
*)applicationDocumentsDirectory;
-(void)saveContext
{
NSError *error = nil;
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil) {
if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
}
#pragma mark - Core Data stack
- (NSManagedObjectContext *)managedObjectContext
{
if (__managedObjectContext != nil) {
return__managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [selfpersisteneStoreCoordinator];
if (coordinator != nil) {
__managedObjectContext = [[NSManagedObjectContextalloc] init];
[__managedObjectContextsetPersistentStoreCoordinator:coordinator];
}
return__managedObjectContext;
}
- (NSManagedObjectModel *)managedObjectModel
{
if (__managedObjectModel != nil) {
return__managedObjectModel;
}
// 这里URLForResource:@"lich" 的名字（lich）要和你建立datamodel时候取的名字是一样的
NSURL *modelURL = //[NSURL fileURLWithPath:[@"lich" stringByAppendingPathExtension:@"mom"]];
[[NSBundlemainBundle] URLForResource:@"lich"withExtension:@"momd"];
__managedObjectModel = [[NSManagedObjectModelalloc] initWithContentsOfURL:modelURL];
return__managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persisteneStoreCoordinator
{
if (__persistentStoreCoordinator != nil) {
return__persistentStoreCoordinator;
}
NSString *docs = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSURL *storURL = [NSURLfileURLWithPath:[docs stringByAppendingPathComponent:@"lich.sqlite"]];
// 这个lich.sqlite名字无限制，就是一个数据库文件的名字
// NSURL *storeNRL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"lich.sqlite"];
// NSLog(@"storURL : %@", storeNRL);
// NSLog(@"store : %@", storURL);
NSError *error = nil;
__persistentStoreCoordinator = [[NSPersistentStoreCoordinatoralloc] initWithManagedObjectModel:[selfmanagedObjectModel]];
if (![__persistentStoreCoordinatoraddPersistentStoreWithType:NSSQLiteStoreTypeconfiguration:nilURL:storURL options:nilerror:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return__persistentStoreCoordinator;
}
- (void)applicationWillTerminate:(UIApplication *)application
{
// Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
[selfsaveContext];
}
// 按保存按钮，保存数据
- (void)addButtonPressed
{
[self.titleFieldresignFirstResponder];
[self.ageFieldresignFirstResponder];
Entity *entity = (Entity *) [NSEntityDescriptioninsertNewObjectForEntityForName:@"Entity"inManagedObjectContext:self.context];
[entity setTitle:self.titleField.text];
[entity setAge:[NSNumbernumberWithInt:[self.ageField.textintValue]]];
NSError *error;
BOOL isSaveSuccess = [self.contextsave:&error];
if (isSaveSuccess) {
NSLog(@"save successful!");
} else {
NSLog(@"Error : %@, %@ ", error, [error userInfo]);
}
}
// 按查找按钮，掏出数据
- (void)queryButtonPressed
{
// 创建取回数据请求
NSFetchRequest *request = [[[NSFetchRequestalloc] init] autorelease];
// 设置要检索的数据类型
NSEntityDescription *des = [NSEntityDescriptionentityForName:@"Entity"inManagedObjectContext:self.context];
// 设置请求实体
[request setEntity:des];
// 指定结果的排序方式
NSSortDescriptor *sortDescriptor = [[[NSSortDescriptoralloc] initWithKey:@"age"ascending:NO] autorelease];
NSArray *sortDescriptions = [[[NSArrayalloc] initWithObjects:sortDescriptor, nil] autorelease];
[request setSortDescriptors:sortDescriptions];
NSError *error = nil;
NSMutableArray *mutableFetchResult = [[self.contextexecuteFetchRequest:request error:&error] mutableCopy];
if (mutableFetchResult == nil) {
NSLog(@"Error : %@ , %@", error, [error userInfo]);
}
self.entities = mutableFetchResult;
NSLog(@"The count of entry: %d", [self.entitiescount]);
for (Entity *entity inself.entities) {
NSLog(@"Title : %@ --------- Age: %d", entity.title, [entity.ageintValue]);
}
[mutableFetchResult release];
}
文章结束给大家分享下程序员的一些笑话语录：
人在天涯钻，哪儿能不挨砖？日啖板砖三百颗，不辞长做天涯人～
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文件和数据
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