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以代码实例总结iOS应用开发中数据的存储方式

程序员文章站 2023-01-01 19:30:28
ios数据存储包括以下几种存储机制: 属性列表 对象归档 sqlite3 coredata appsettings 普通文件存储...

ios数据存储包括以下几种存储机制:

  • 属性列表
  • 对象归档
  • sqlite3
  • coredata
  • appsettings
  • 普通文件存储

1、属性列表

复制代码 代码如下:

// 
//  persistence1viewcontroller.h 
//  persistence1 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import <uikit/uikit.h> 
#define kfilename @"data.plist" 
 
@interface persistence1viewcontroller : uiviewcontroller { 
    uitextfield *filed1; 
    uitextfield *field2; 
    uitextfield *field3; 
    uitextfield *field4; 

@property (nonatomic, retain) iboutlet uitextfield *field1; 
@property (nonatomic, retain) iboutlet uitextfield *field2; 
@property (nonatomic, retain) iboutlet uitextfield *field3; 
@property (nonatomic, retain) iboutlet uitextfield *field4; 
 
- (nsstring *)datafilepath; 
- (void)applicationwillresignactive:(nsnotification *)notification; 
 
@end 

复制代码 代码如下:

// 
//  persistence1viewcontroller.m 
//  persistence1 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import "persistence1viewcontroller.h" 
 
@implementation persistence1viewcontroller 
@synthesize field1; 
@synthesize field2; 
@synthesize field3; 
@synthesize field4; 
 
//数据文件的完整路径 
- (nsstring *)datafilepath { 
    //检索documents目录路径。第二个参数表示将搜索限制在我们的应用程序沙盒中 
    nsarray *paths = nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes); 
    //每个应用程序只有一个documents目录 
    nsstring *documentsdirectory = [paths objectatindex:0]; 
    //创建文件名 
    return [documentsdirectory stringbyappendingpathcomponent:kfilename]; 

 
//应用程序退出时,将数据保存到属性列表文件 
- (void)applicationwillresignactive:(nsnotification *)notification { 
    nsmutablearray *array = [[nsmutablearray alloc] init]; 
    [array addobject: field1.text]; 
    [array addobject: field2.text]; 
    [array addobject: field3.text]; 
    [array addobject: field4.text]; 
    [array writetofile:[self datafilepath] atomically:yes]; 
    [array release]; 

 
/*
// the designated initializer. override to perform setup that is required before the view is loaded.
- (id)initwithnibname:(nsstring *)nibnameornil bundle:(nsbundle *)nibbundleornil {
    self = [super initwithnibname:nibnameornil bundle:nibbundleornil];
    if (self) {
        // custom initialization
    }
    return self;
}
*/ 
 
/*
// implement loadview to create a view hierarchy programmatically, without using a nib.
- (void)loadview {
}
*/ 
 
 
 
// implement viewdidload to do additional setup after loading the view, typically from a nib. 
- (void)viewdidload { 
    [super viewdidload]; 
    nsstring *filepath = [self datafilepath]; 
    //检查数据文件是否存在 
    if([[nsfilemanager defaultmanager] fileexistsatpath:filepath]) { 
        nsarray *array = [[nsarray alloc] initwithcontentsoffile:filepath]; 
        field1.text = [array objectatindex:0]; 
        field2.text = [array objectatindex:1]; 
        field3.text = [array objectatindex:2]; 
        field4.text = [array objectatindex:3]; 
        [array release]; 
    } 
    uiapplication *app = [uiapplication sharedapplication]; 
    [[nsnotificationcenter defaultcenter] addobserver:self 
                                            selector:@selector(applicationwillresignactive:) 
                                            name:uiapplicationwillresignactivenotification 
                                            object:app]; 
    [super viewdidload]; 

 
 
/*
// override to allow orientations other than the default portrait orientation.
- (bool)shouldautorotatetointerfaceorientation:(uiinterfaceorientation)interfaceorientation {
    // return yes for supported orientations
    return (interfaceorientation == uiinterfaceorientationportrait);
}
*/ 
 
- (void)didreceivememorywarning { 
    // releases the view if it doesn't have a superview. 
    [super didreceivememorywarning]; 
     
    // release any cached data, images, etc that aren't in use. 

 
- (void)viewdidunload { 
    self.field1 = nil; 
    self.field2 = nil; 
    self.field3 = nil; 
    self.field4 = nil; 
    [super viewdidunload]; 

 
 
- (void)dealloc { 
    [field1 release]; 
    [field2 release]; 
    [field3 release]; 
    [field4 release]; 
    [super dealloc]; 

 
@end 

2、对象归档

复制代码 代码如下:

// 
//  fourlines.h 
//  persistence2 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import <foundation/foundation.h> 
 
@interface fourlines : nsobject <nscoding, nscopying> { 
    nsstring *field1; 
    nsstring *field2; 
    nsstring *field3; 
    nsstring *field4; 

@property (nonatomic, retain) nsstring *field1; 
@property (nonatomic, retain) nsstring *field2; 
@property (nonatomic, retain) nsstring *field3; 
@property (nonatomic, retain) nsstring *field4; 
 

@end 


复制代码 代码如下:

// 
//  fourlines.m 
//  persistence2 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import "fourlines.h" 
 
#define kfield1key @"field1" 
#define kfield2key @"field2" 
#define kfield3key @"field3" 
#define kfield4key @"field4" 
 
@implementation fourlines 
@synthesize field1; 
@synthesize field2; 
@synthesize field3; 
@synthesize field4; 
 
#pragma mark nscoding 
- (void)encodewithcoder:(nscoder *)acoder { 
    [acoder encodeobject:field1 forkey:kfield1key]; 
    [acoder encodeobject:field2 forkey:kfield2key]; 
    [acoder encodeobject:field3 forkey:kfield3key]; 
    [acoder encodeobject:field4 forkey:kfield4key]; 

 
-(id) initwithcoder:(nscoder *)adecoder { 
    if(self = [super init]) { 
        field1 = [[adecoder decodeobjectforkey:kfield1key] retain]; 
        field2 = [[adecoder decodeobjectforkey:kfield2key] retain]; 
        field3 = [[adecoder decodeobjectforkey:kfield3key] retain]; 
        field4 = [[adecoder decodeobjectforkey:kfield4key] retain]; 
    } 
    return self; 

 
#pragma mark - 
#pragma mark nscopying 
- (id) copywithzone:(nszone *)zone { 
    fourlines *copy = [[[self class] allocwithzone: zone] init]; 
    copy.field1 = [[self.field1 copywithzone: zone] autorelease]; 
    copy.field2 = [[self.field2 copywithzone: zone] autorelease]; 
    copy.field3 = [[self.field3 copywithzone: zone] autorelease]; 
    copy.field4 = [[self.field4 copywithzone: zone] autorelease]; 
    return copy; 

@end 

复制代码 代码如下:

// 
//  persistence2viewcontroller.h 
//  persistence2 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import <uikit/uikit.h> 
#define kfilename @"archive" 
#define kdatakey @"data" 
 
@interface persistence2viewcontroller : uiviewcontroller { 
    uitextfield *filed1; 
    uitextfield *field2; 
    uitextfield *field3; 
    uitextfield *field4; 

@property (nonatomic, retain) iboutlet uitextfield *field1; 
@property (nonatomic, retain) iboutlet uitextfield *field2; 
@property (nonatomic, retain) iboutlet uitextfield *field3; 
@property (nonatomic, retain) iboutlet uitextfield *field4; 
 
- (nsstring *)datafilepath; 
- (void)applicationwillresignactive:(nsnotification *)notification; 
 
@end 

复制代码 代码如下:

// 
//  persistence2viewcontroller.m 
//  persistence2 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import "persistence2viewcontroller.h" 
#import "fourlines.h" 
 
@implementation persistence2viewcontroller 
@synthesize field1; 
@synthesize field2; 
@synthesize field3; 
@synthesize field4; 
 
//数据文件的完整路径 
- (nsstring *)datafilepath { 
    //检索documents目录路径。第二个参数表示将搜索限制在我们的应用程序沙盒中 
    nsarray *paths = nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes); 
    //每个应用程序只有一个documents目录 
    nsstring *documentsdirectory = [paths objectatindex:0]; 
    //创建文件名 
    return [documentsdirectory stringbyappendingpathcomponent:kfilename]; 

 
//应用程序退出时,将数据保存到属性列表文件 
- (void)applicationwillresignactive:(nsnotification *)notification { 
    fourlines *fourlines = [[fourlines alloc] init]; 
    fourlines.field1 = field1.text; 
    fourlines.field2 = field2.text; 
    fourlines.field3 = field3.text; 
    fourlines.field4 = field4.text; 
     
    nsmutabledata *data = [[nsmutabledata alloc] init];//用于存储编码的数据 
    nskeyedarchiver *archiver = [[nskeyedarchiver alloc] initforwritingwithmutabledata:data]; 
     
    [archiver encodeobject:fourlines forkey:kdatakey]; 
    [archiver finishencoding]; 
    [data writetofile:[self datafilepath] atomically:yes]; 
     
    [fourlines release]; 
    [archiver release]; 
    [data release]; 

 
/*
 // the designated initializer. override to perform setup that is required before the view is loaded.
 - (id)initwithnibname:(nsstring *)nibnameornil bundle:(nsbundle *)nibbundleornil {
 self = [super initwithnibname:nibnameornil bundle:nibbundleornil];
 if (self) {
 // custom initialization
 }
 return self;
 }
 */ 
 
/*
 // implement loadview to create a view hierarchy programmatically, without using a nib.
 - (void)loadview {
 }
 */ 
 
 
 
// implement viewdidload to do additional setup after loading the view, typically from a nib. 
- (void)viewdidload { 
    [super viewdidload]; 
    nsstring *filepath = [self datafilepath]; 
    //检查数据文件是否存在 
    if([[nsfilemanager defaultmanager] fileexistsatpath:filepath]) { 
         
        //从文件获取用于解码的数据 
        nsdata *data = [[nsmutabledata alloc] initwithcontentsoffile:[self datafilepath]]; 
        nskeyedunarchiver *unarchiver = [[nskeyedunarchiver alloc] initforreadingwithdata:data]; 
         
        fourlines *fourlines = [unarchiver decodeobjectforkey:kdatakey]; 
        [unarchiver finishdecoding]; 
         
        field1.text = fourlines.field1; 
        field2.text = fourlines.field2; 
        field3.text = fourlines.field3; 
        field4.text = fourlines.field4; 
         
        [unarchiver release]; 
        [data release]; 
    } 
    uiapplication *app = [uiapplication sharedapplication]; 
    [[nsnotificationcenter defaultcenter] addobserver:self 
                                             selector:@selector(applicationwillresignactive:) 
                                             name:uiapplicationwillresignactivenotification 
                                             object:app]; 
    [super viewdidload]; 

 
 
/*
 // override to allow orientations other than the default portrait orientation.
 - (bool)shouldautorotatetointerfaceorientation:(uiinterfaceorientation)interfaceorientation {
 // return yes for supported orientations
 return (interfaceorientation == uiinterfaceorientationportrait);
 }
 */ 
 
- (void)didreceivememorywarning { 
    // releases the view if it doesn't have a superview. 
    [super didreceivememorywarning]; 
     
    // release any cached data, images, etc that aren't in use. 

 
- (void)viewdidunload { 
    self.field1 = nil; 
    self.field2 = nil; 
    self.field3 = nil; 
    self.field4 = nil; 
    [super viewdidunload]; 

 
 
- (void)dealloc { 
    [field1 release]; 
    [field2 release]; 
    [field3 release]; 
    [field4 release]; 
    [super dealloc]; 

@end 

3、sqlite

复制代码 代码如下:

// 
//  persistence3viewcontroller.h 
//  persistence3 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import <uikit/uikit.h> 
#define kfilename @"data.sqlite3" 
 
@interface persistence3viewcontroller : uiviewcontroller { 
    uitextfield *filed1; 
    uitextfield *field2; 
    uitextfield *field3; 
    uitextfield *field4; 

@property (nonatomic, retain) iboutlet uitextfield *field1; 
@property (nonatomic, retain) iboutlet uitextfield *field2; 
@property (nonatomic, retain) iboutlet uitextfield *field3; 
@property (nonatomic, retain) iboutlet uitextfield *field4; 
 
- (nsstring *)datafilepath; 
- (void)applicationwillresignactive:(nsnotification *)notification; 
@end 

复制代码 代码如下:

// 
//  persistence3viewcontroller.m 
//  persistence3 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import "persistence3viewcontroller.h" 
#import <sqlite3.h> 
 
@implementation persistence3viewcontroller 
@synthesize field1; 
@synthesize field2; 
@synthesize field3; 
@synthesize field4; 
 
//数据文件的完整路径 
- (nsstring *)datafilepath { 
    //检索documents目录路径。第二个参数表示将搜索限制在我们的应用程序沙盒中 
    nsarray *paths = nssearchpathfordirectoriesindomains(nsdocumentdirectory, nsuserdomainmask, yes); 
    //每个应用程序只有一个documents目录 
    nsstring *documentsdirectory = [paths objectatindex:0]; 
    //创建文件名 
    return [documentsdirectory stringbyappendingpathcomponent:kfilename]; 

 
//应用程序退出时,将数据保存到属性列表文件 
- (void)applicationwillresignactive:(nsnotification *)notification { 
    sqlite3 *database; 
    if(sqlite3_open([[self datafilepath] utf8string], &database) != sqlite_ok) { 
        sqlite3_close(database); 
        nsassert(0, @"failed to open database"); 
    } 
     
    for(int i = 1; i <= 4; i++) { 
        nsstring *fieldname = [[nsstring alloc] initwithformat:@"field%d", i]; 
        uitextfield *field = [self valueforkey:fieldname]; 
        [fieldname release]; 
         
        char *update = "insert or replace into fields (row, field_data) values (?, ?);"; 
        sqlite3_stmt *stmt; 
        //将sql语句编译为sqlite内部一个结构体(sqlite3_stmt),类似java jdbc的preparedstatement预编译 
        if (sqlite3_prepare_v2(database, update, -1, &stmt, nil) == sqlite_ok) { 
            //在bind参数的时候,参数列表的index从1开始,而取出数据的时候,列的index是从0开始 
            sqlite3_bind_int(stmt, 1, i); 
            sqlite3_bind_text(stmt, 2, [field.text utf8string], -1, null); 
        } else { 
            nsassert(0, @"error:failed to prepare statemen"); 
        } 
        //执行sql文,获取结果  
        int result = sqlite3_step(stmt); 
        if(result != sqlite_done) { 
            nsassert1(0, @"error updating table: %d", result); 
        } 
        //释放stmt占用的内存(sqlite3_prepare_v2()分配的) 
        sqlite3_finalize(stmt); 
    } 
    sqlite3_close(database); 

 
/*
 // the designated initializer. override to perform setup that is required before the view is loaded.
 - (id)initwithnibname:(nsstring *)nibnameornil bundle:(nsbundle *)nibbundleornil {
 self = [super initwithnibname:nibnameornil bundle:nibbundleornil];
 if (self) {
 // custom initialization
 }
 return self;
 }
 */ 
 
/*
 // implement loadview to create a view hierarchy programmatically, without using a nib.
 - (void)loadview {
 }
 */ 
 
 
 
// implement viewdidload to do additional setup after loading the view, typically from a nib. 
- (void)viewdidload { 
    [super viewdidload]; 
    nsstring *filepath = [self datafilepath]; 
    //检查数据文件是否存在 
    if([[nsfilemanager defaultmanager] fileexistsatpath:filepath]) { 
        //打开数据库 
        sqlite3 *database; 
        if(sqlite3_open([filepath utf8string], &database) != sqlite_ok) { 
            sqlite3_close(database); 
            nsassert(0, @"failed to open database"); 
        } 
         
        //创建表 
        char *errormsg; 
        nsstring *createsql =  
            @"create table if not exists fields (row integer primary key, field_data text);"; 
        if(sqlite3_exec(database, [createsql utf8string], null, null, &errormsg) != sqlite_ok) { 
            sqlite3_close(database); 
            nsassert(0, @"error creating table: %s", errormsg); 
        } 
 
        //查询 
        nsstring *query = @"select row, field_data from fields order by row"; 
        sqlite3_stmt *statement; 
        //设置nbyte可以加速操作 
        if(sqlite3_prepare_v2(database, [query utf8string], -1, &statement, nil) == sqlite_ok) { 
            while (sqlite3_step(statement) == sqlite_row) {//返回每一行 
                int row = sqlite3_column_int(statement, 0); 
                char *rowdata = (char *)sqlite3_column_text(statement, 1); 
                 
                nsstring *fieldname = [[nsstring alloc] initwithformat:@"field%d", row]; 
                nsstring *fieldvalue = [[nsstring alloc] initwithutf8string:rowdata]; 
                 
                uitextfield *field = [self valueforkey:fieldname]; 
                field.text = fieldvalue; 
                 
                [fieldname release]; 
                [fieldvalue release]; 
            } 
            //释放statement占用的内存(sqlite3_prepare()分配的) 
            sqlite3_finalize(statement); 
        } 
        sqlite3_close(database); 
    } 
     
     
    uiapplication *app = [uiapplication sharedapplication]; 
    [[nsnotificationcenter defaultcenter] addobserver:self 
                                             selector:@selector(applicationwillresignactive:) 
                                                 name:uiapplicationwillresignactivenotification 
                                               object:app]; 
    [super viewdidload]; 

 
 
/*
 // override to allow orientations other than the default portrait orientation.
 - (bool)shouldautorotatetointerfaceorientation:(uiinterfaceorientation)interfaceorientation {
 // return yes for supported orientations
 return (interfaceorientation == uiinterfaceorientationportrait);
 }
 */ 
 
- (void)didreceivememorywarning { 
    // releases the view if it doesn't have a superview. 
    [super didreceivememorywarning]; 
     
    // release any cached data, images, etc that aren't in use. 

 
- (void)viewdidunload { 
    self.field1 = nil; 
    self.field2 = nil; 
    self.field3 = nil; 
    self.field4 = nil; 
    [super viewdidunload]; 

 
 
- (void)dealloc { 
    [field1 release]; 
    [field2 release]; 
    [field3 release]; 
    [field4 release]; 
    [super dealloc]; 

 
@end 

4、core data

复制代码 代码如下:

// 
//  persistenceviewcontroller.h 
//  persistence4 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import <uikit/uikit.h> 
 
 
@interface persistenceviewcontroller : uiviewcontroller { 
    uitextfield *filed1; 
    uitextfield *field2; 
    uitextfield *field3; 
    uitextfield *field4; 

@property (nonatomic, retain) iboutlet uitextfield *field1; 
@property (nonatomic, retain) iboutlet uitextfield *field2; 
@property (nonatomic, retain) iboutlet uitextfield *field3; 
@property (nonatomic, retain) iboutlet uitextfield *field4; 
 
@end 

复制代码 代码如下:

// 
//  persistenceviewcontroller.m 
//  persistence4 
// 
//  created by liu lavy on 11-10-3. 
//  copyright 2011 __mycompanyname__. all rights reserved. 
// 
 
#import "persistenceviewcontroller.h" 
#import "persistence4appdelegate.h" 
 
@implementation persistenceviewcontroller 
@synthesize field1; 
@synthesize field2; 
@synthesize field3; 
@synthesize field4; 
 
 
-(void) applicationwillresignactive:(nsnotification *)notification { 
    persistence4appdelegate *appdelegate = [[uiapplication sharedapplication] delegate]; 
    nsmanagedobjectcontext *context = [appdelegate managedobjectcontext]; 
    nserror *error; 
    for(int i = 1; i <= 4; i++) { 
        nsstring *fieldname = [nsstring stringwithformat:@"field%d", i]; 
        uitextfield *thefield = [self valueforkey:fieldname]; 
         
        //创建提取请求 
        nsfetchrequest *request = [[nsfetchrequest alloc] init]; 
        //创建实体描述并关联到请求 
        nsentitydescription *entitydescription = [nsentitydescription entityforname:@"line" 
                                                             inmanagedobjectcontext:context]; 
        [request setentity:entitydescription]; 
         
        //设置检索数据的条件 
        nspredicate *pred = [nspredicate predicatewithformat:@"(linenum = %d)", i]; 
        [request setpredicate:pred]; 
         
        nsmanagedobject *theline = nil; 
        ////检查是否返回了标准匹配的对象,如果有则加载它,如果没有则创建一个新的托管对象来保存此字段的文本 
        nsarray *objects = [context executefetchrequest:request error:&error]; 
        if(!objects) { 
            nslog(@"there was an error"); 
        } 
        //if(objects.count > 0) { 
        //  theline = [objects objectatindex:0]; 
        //} else { 
            //创建一个新的托管对象来保存此字段的文本 
            theline = [nsentitydescription insertnewobjectforentityforname:@"line" 
                                                    inmanagedobjectcontext:context]; 
            [theline setvalue:[nsnumber numberwithint:i] forkey:@"linenum"]; 
            [theline setvalue:thefield.text forkey:@"linetext"]; 
        //} 
        [request release]; 
    } 
    //通知上下文保存更改 
    [context save:&error]; 
     

 
// the designated initializer.  override if you create the controller programmatically and want to perform customization that is not appropriate for viewdidload. 
/*
- (id)initwithnibname:(nsstring *)nibnameornil bundle:(nsbundle *)nibbundleornil {
    self = [super initwithnibname:nibnameornil bundle:nibbundleornil];
    if (self) {
        // custom initialization.
    }
    return self;
}
*/ 
 
 
// implement viewdidload to do additional setup after loading the view, typically from a nib. 
- (void)viewdidload { 
    persistence4appdelegate *appdelegate = [[uiapplication sharedapplication] delegate]; 
     
    nsmanagedobjectcontext *context = [appdelegate managedobjectcontext]; 
    //创建一个实体描述 
    nsentitydescription *entitydescription = [nsentitydescription entityforname:@"line" inmanagedobjectcontext:context]; 
    //创建一个请求,用于提取对象 
    nsfetchrequest *request = [[nsfetchrequest alloc] init]; 
    [request setentity:entitydescription]; 
     
    //检索对象 
    nserror *error; 
    nsarray *objects = [context executefetchrequest:request error:&error]; 
    if(!objects) { 
        nslog(@"there was an error!"); 
    } 
    for(nsmanagedobject *obj in objects) { 
        nsnumber *linenum = [obj valueforkey:@"linenum"]; 
        nsstring *linetext = [obj valueforkey:@"linetext"]; 
        nsstring *fieldname = [nsstring stringwithformat:@"field%d", [linenum integervalue]]; 
        uitextfield *textfield = [self valueforkey:fieldname]; 
        textfield.text = linetext; 
    } 
    [request release]; 
     
    uiapplication *app = [uiapplication sharedapplication]; 
    [[nsnotificationcenter defaultcenter] addobserver:self  
                                             selector:@selector(applicationwillresignactive:)  
                                                 name:uiapplicationwillresignactivenotification 
                                               object:app]; 
    [super viewdidload]; 

 
/*
// override to allow orientations other than the default portrait orientation.
- (bool)shouldautorotatetointerfaceorientation:(uiinterfaceorientation)interfaceorientation {
    // return yes for supported orientations.
    return (interfaceorientation == uiinterfaceorientationportrait);
}
*/ 
 
- (void)didreceivememorywarning { 
    // releases the view if it doesn't have a superview. 
    [super didreceivememorywarning]; 
     
    // release any cached data, images, etc. that aren't in use. 

 
- (void)viewdidunload { 
    self.field1 = nil; 
    self.field2 = nil; 
    self.field3 = nil; 
    self.field4 = nil; 
    [super viewdidunload]; 

 
 
- (void)dealloc { 
    [field1 release]; 
    [field2 release]; 
    [field3 release]; 
    [field4 release]; 
    [super dealloc]; 

 
 
 
@end 

5、appsettings
复制代码 代码如下:

nsuserdefaults *defaults = [nsuserdefaults standarduserdefaults]; 

6、普通文件存储

这种方式即自己将数据通过io保存到文件,或从文件读取。