本文发布在http://he8090.cn/2016/07/18/iOS数据持久化/
1、保存到本地Plist文件
- (IBAction)plistSave:(UIButton *)sender {
//获取沙盒路径
NSString *sandBoxPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
//新建路径存储plist文件
NSString *plistPath = [sandBoxPath stringByAppendingString:@"/StudentInfo.plist"];
//申明根数组
NSMutableArray *rootArray = nil;
//判断沙盒路径是否存在,根据沙盒路径初始化数组,不存在初始化数组
if ([[NSFileManager defaultManager] fileExistsAtPath:plistPath]) {
//根据沙盒路径初始化数组
rootArray = [NSMutableArray arrayWithContentsOfFile:plistPath];
}else{
rootArray = [NSMutableArray array];
}
//打包数据信息
if (self.name.text.length == 0 || self.age.text.length == 0 || self.grade.text.length == 0) {
NSLog(@"信息不完整,存储失败");
}else{
NSDictionary *dic = @{@"name":self.name.text,@"age":self.age.text,@"grade":self.grade.text};
[rootArray addObject:dic];
}
//存入plist文件
if ([rootArray writeToFile:plistPath atomically:YES]) {
NSLog(@"存储成功");
}else{
NSLog(@"存储失败");
}
NSLog(@"%@",plistPath);
}
2、从plist文件中读取数据
- (IBAction)plistFetch:(UIButton *)sender {
//获取沙盒路径
NSString *sandBoxPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
//新建路径存储plist文件
NSString *plistPath = [sandBoxPath stringByAppendingString:@"/StudentInfo.plist"];
//申明根数组
NSMutableArray *rootArray = nil;
//判断沙盒路径是否存在,根据沙盒路径初始化数组,不存在初始化数组
if ([[NSFileManager defaultManager] fileExistsAtPath:plistPath]) {
//根据沙盒路径初始化数组
rootArray = [NSMutableArray arrayWithContentsOfFile:plistPath];
}else{
rootArray = [NSMutableArray array];
}
//判断输入信息是否存在
for (NSDictionary *dic in rootArray) {
if ([dic[@"name"] isEqualToString:self.name.text]) {
NSLog(@"用户存在");
}
}
}
3、删除Plist文件
- (IBAction)plistDeleted:(UIButton *)sender {
//获取沙盒路径
NSString *sandBoxPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
//新建路径存储plist文件
NSString *plistPath = [sandBoxPath stringByAppendingString:@"/StudentInfo.plist"];
//申明根数组
NSMutableArray *rootArray = nil;
//判断沙盒路径是否存在,根据沙盒路径初始化数组,不存在初始化数组
if ([[NSFileManager defaultManager] fileExistsAtPath:plistPath]) {
//根据沙盒路径初始化数组
rootArray = [NSMutableArray arrayWithContentsOfFile:plistPath];
}else{
rootArray = [NSMutableArray array];
}
}
4、沙盒文件目录获取代码
//Home
//Home目录
NSString *homeDirectory = NSHomeDirectory();
//Document
//Document目录
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path = [paths objectAtIndex:0];
//Cache
//Cache目录
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *path = [paths objectAtIndex:0];
//Libary目录
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
NSString *path = [paths objectAtIndex:0];
5、图片存入plist (需要转换)
//获取沙盒路径,
NSString *path_sandox = NSHomeDirectory();
//创建一个存储plist文件的路径
NSString *newPath = [path_sandox stringByAppendingPathComponent:@/Documents/pic.plist];
NSMutableArray *arr = [[NSMutableArray alloc] init];
UIImage *image = [UIImage imageNamed:@"1.png"];
/*
把图片转换为Base64的字符串
在iphone上有两种读取图片数据的简单方法: UIImageJPEGRepresentation和UIImagePNGRepresentation.
UIImageJPEGRepresentation函数需要两个参数:图片的引用和压缩系数.而UIImagePNGRepresentation只需要图片引用作为参数.通过在实际使用过程中,
比较发现: UIImagePNGRepresentation(UIImage* image) 要比UIImageJPEGRepresentation(UIImage* image, 1.0) 返回的图片数据量大很多.
譬如,同样是读取摄像头拍摄的同样景色的照片, UIImagePNGRepresentation()返回的数据量大小为199K ,
而 UIImageJPEGRepresentation(UIImage* image, 1.0)返回的数据量大小只为140KB,比前者少了50多KB.
如果对图片的清晰度要求不高,还可以通过设置 UIImageJPEGRepresentation函数的第二个参数,大幅度降低图片数据量.譬如,刚才拍摄的图片,
通过调用UIImageJPEGRepresentation(UIImage* image, 1.0)读取数据时,返回的数据大小为140KB,但更改压缩系数后,
通过调用UIImageJPEGRepresentation(UIImage* image, 0.5)读取数据时,返回的数据大小只有11KB多,大大压缩了图片的数据量 ,
而且从视角角度看,图片的质量并没有明显的降低.因此,在读取图片数据内容时,建议优先使用UIImageJPEGRepresentation,
并可根据自己的实际使用场景,设置压缩系数,进一步降低图片数据量大小.
*/
NSData *_data = UIImageJPEGRepresentation(image, 1.0f);
//将图片的data转化为字符串
NSString *strimage64 = [_data base64EncodedString];
[arr addObject:image64];
//写入plist文件
if ([arr writeToFile:newPath atomically:YES]) {
NSLog(@"写入成功");
};
//可以到沙河路径下查看plist文件中的图片数据
//这样就存起来的,然后用到的时候再利用存储的字符串转化为图片
//NSData *_decodedImageData = [[NSData alloc] initWithBase64Encoding:image64]; 这是iOS7之前的一个方法
NSData *_decodedImageData = [[NSData alloc]initWithBase64EncodedString:strimage64 options:NSDataBase64DecodingIgnoreUnknownCharacters];
UIImage *_decodedImage = [UIImage imageWithData:_decodedImageData];
//可以打印下图片是否存在
NSLog(@"===Decoded image size: %@", NSStringFromCGSize(_decodedImage.size));
6、把图片直接保存到沙盒中,然后再把路径存储起来,等到用图片的时候先获取图片的路径,再通过路径拿到图片。
(1)
//拿到图片
UIImage *image2 = [UIImage imageNamed:@"1.png"];
NSString *path_document = NSHomeDirectory();
//设置一个图片的存储路径
NSString *imagePath = [path_document stringByAppendingString:@"/Documents/pic.png"];
//把图片直接保存到指定的路径(同时应该把图片的路径imagePath存起来,下次就可以直接用来取)
[UIImagePNGRepresentation(image2) writeToFile:imagePath atomically:YES];
(2)通过地址取图片
UIImage *getimage2 = [UIImage imageWithContentsOfFile:imagePath];
NSLog(@"image2 is size %@",NSStringFromCGSize(getimage2.size));
7、归档(序列化)
(1)归档的类遵守NSCoding协议。
(2)实现encodeWithCoder 和initWithCoder方法。
(3)根据地址进行操作。
好处:可以压缩存放。
//归档操作
BOOL archiver = [NSKeyedArchiver archiveRootObject:per toFile:self.savePath];
8、CoreData
(1)配置上下文NSManagedObjectContext:在内存中开辟一个空间,用于专门处理某件事情,结束之后去内存中读取上下文。链接不同功能模块,保证模块独立性。(NSPrivateQueueConcurrencyType私有队列,开辟新的线程池,不阻塞主线程。NSMainQueueConcurrencyType主队列)。
NSManagedObjectContext * context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
//配置存储调度器
//a.从程序中加载模型
NSManagedObjectModel * model = [NSManagedObjectModel mergedModelFromBundles:nil];
NSPersistentStoreCoordinator * store = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];
//b.配置存储调度器存储路径
NSURL *url = [NSURL fileURLWithPath:self.keyPath];
[store addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:nil error:nil];
//将调度器赋值给上下文
context.persistentStoreCoordinator = store;
_context = context;
(2)增删改查
- (IBAction)action_btn:(UIButton *)sender {
switch (sender.tag) {
case 101:
{
//插入
Person *person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:self.context];
person.name = self.name.text;
person.phone = self.phone.text;
//保存上下文
[self.context save:nil];
}
break;
case 102:
{
//删除
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];
//在上下文中查找
NSArray *array = [self.context executeFetchRequest:request error:nil];
//匹配数据
for (Person *per in array) {
if ([per.name isEqualToString:@"12"]) {
[self.context deleteObject:per];
}
}
//数据保存
[self.context save:nil];
}
break;
case 103:
{
//修改
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];
//在上下文中查找
NSArray *array = [self.context executeFetchRequest:request error:nil];
//匹配数据
for (Person *per in array) {
if ([per.name isEqualToString:@"12"]) {
per.name = @"张三";
}
}
//数据保存
[self.context save:nil];
}
break;
case 104:
{
//配置查找条件
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Person"];
request.fetchLimit = 10;//查询长度
request.fetchOffset = 0;//查询起始点
//查询条件
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name==%@",@"zhangsan"];
request.predicate = predicate;
//在上下文中查找
NSArray *array = [self.context executeFetchRequest:request error:nil];
NSLog(@"%@",array);
}
break;
default:
break;
}
}
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