ios 沙盒 NSCoding 归档 数据存储

转自：http://www.maxiaoguo.com/clothes/232.html

NSCoding 跟其他存储方式略有不同，他可以存储对象

对象存储的条件是： 对象需要遵守 NSCoding 协议
存储的时候需要 调用 encodeWithCoder 方法
读取的时候需要调用initWithCoder 方法
[NSKeyedArchiver archiveRootObject:stu toFile:path]; 存储 

NSKeyedUnarchiver unarchiveObjectWithFile:path 读取

对象代码

#import <Foundation/Foundation.h>@interface MJStudent : NSObject  <NSCoding>@property (nonatomic, copy) NSString *no;@property (nonatomic, assign) double height;@property (nonatomic, assign) int age;@end

#import "MJStudent.h"@interface MJStudent() @end@implementation MJStudent/** *  将某个对象写入文件时会调用 *  在这个方法中说清楚哪些属性需要存储 */- (void)encodeWithCoder:(NSCoder *)encoder{    [encoder encodeObject:self.no forKey:@"no"];    [encoder encodeInt:self.age forKey:@"age"];    [encoder encodeDouble:self.height forKey:@"height"];}/** *  从文件中解析对象时会调用 *  在这个方法中说清楚哪些属性需要存储 */- (id)initWithCoder:(NSCoder *)decoder{    if (self = [super init]) {        // 读取文件的内容        self.no = [decoder decodeObjectForKey:@"no"];        self.age = [decoder decodeIntForKey:@"age"];        self.height = [decoder decodeDoubleForKey:@"height"];    }    return self;}@end

保存读取

- (IBAction)save {    // 1.新的模型对象    MJStudent *stu = [[MJStudent alloc] init];    stu.no = @"42343254";    stu.age = 20;    stu.height = 1.55;        // 2.归档模型对象    // 2.1.获得Documents的全路径    NSString *doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];    // 2.2.获得文件的全路径    NSString *path = [doc stringByAppendingPathComponent:@"stu.data"];    // 2.3.将对象归档    [NSKeyedArchiver archiveRootObject:stu toFile:path];}- (IBAction)read {    // 1.获得Documents的全路径    NSString *doc = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];    // 2.获得文件的全路径    NSString *path = [doc stringByAppendingPathComponent:@"stu.data"];        // 3.从文件中读取MJStudent对象    MJStudent *stu = [NSKeyedUnarchiver unarchiveObjectWithFile:path];        NSLog(@"%@ %d %f", stu.no, stu.age, stu.height);}