NSArray *myPaths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
//NSDocumentDirectory 是表示沙盒里 document 文件夹的列表
//NSDocumentionDirectory 是 获取 沙盒里 library 里 documention里的文件夹列表
NSString *path=[myPaths objectAtIndex:0]; // objectAtIndex : 为document 的文件列表
NSString *filename=[path stringByAppendingPathComponent:@"properties.plist"];
-(IBAction)save:(id)sender
{
NSArray *myPaths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path=[myPaths objectAtIndex:0];
NSString *filename=[path stringByAppendingPathComponent:@"properties.plist"];
NSMutableArray *array=[[NSMutableArray alloc] init];
[array addObject:txt_name.text];
[array addObject:txt_class.text];
[array addObject:txt_id.text];
[array writeToFile:filename atomically:YES];
NSLog(@"come here");
}
-(IBAction)read:(id)sender
{
NSArray *mypaths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path=[mypaths objectAtIndex:0];
NSString *filename=[path stringByAppendingPathComponent:@"properties.plist"];
if([[NSFileManager defaultManager] fileExistsAtPath:filename])
{
NSLog(@"it's ok");
NSMutableArray *array=[[NSMutableArray alloc] initWithContentsOfFile:filename];
txt_name.text=[array objectAtIndex:0];
txt_class.text=[array objectAtIndex:1];
txt_id.text=[array objectAtIndex:2];
}
}
以上是保存到 plist 文件里，但是plist 的文件类型有限制，假如是自定义类的话，难以满足需求。
所以有序列化和反序列化
NSKeyedArchiver 和 NSKeyedUnarchiver
创建一个类 然后 添加两个协议 <NSCoding>
//将对象写入文件中
-(void)encodeWithCoder:(NSCoder *)aCoder
{
[aCoder encodeObject:studentid forKey:@"stuid"];
[aCoder encodeObject:studentname forKey:@"stuname"];
[aCoder encodeObject:studentclass forKey:@"stuclass"];
}
//从文件中读取对象
-(id)initWithCoder:(NSCoder *)aDecoder
{
self.studentid=[aDecoder decodeObjectForKey:@"stuid"];
self.studentname=[aDecoder decodeObjectForKey:@"stuname"];
self.studentclass=[aDecoder decodeObjectForKey:@"stuclass"];
return self;
}
然后在事件中的
-(IBAction)save:(id)sender
{
NSArray *myPaths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path=[myPaths objectAtIndex:0];
NSString *filename=[path stringByAppendingPathComponent:@"student.archive"];
NSMutableData *data=[NSMutableData data];
//NSkeyedArchiver 是将 data 变成 二进制 文件
NSKeyedArchiver *archiver=[[NSKeyedArchiver alloc]initForWritingWithMutableData:data];
student *stu=[[student alloc] init];
stu.studentid=txt_id.text;
stu.studentname=txt_name.text;
stu.studentclass=txt_class.text;
//写入到文件
NSLog(@"%@",stu.studentname);
[archiver encodeObject:stu forKey:@"stu"]; // encodeObject:stu 是调用了 上面的 encodeObject :aCoder 方法
[archiver finishEncoding];
[data writeToFile:filename atomically:YES];
NSLog(@"%@",data);
}
-(IBAction)read:(id)sender
{
NSArray *myPaths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path=[myPaths objectAtIndex:0];
NSString *filename=[path stringByAppendingPathComponent:@"student.archive"];
NSData *data=[NSData dataWithContentsOfFile:filename];
NSLog(@"%@",data);
if([data length]>0)
{
NSKeyedUnarchiver * archiver=[[NSKeyedUnarchiver alloc]initForReadingWithData :data];
student *stu= [archiver decodeObjectForKey:@"stu"]; //decodeObjectForKey 是调用上面 decodeObjectForKey:aCoder方法
txt_name.text=stu.studentname;
txt_id.text=stu.studentid;
txt_class.text=stu.studentclass;
}
}