首先賬號的存儲路徑：
#define JJTAccountPath [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"account.archive"]
模型寫代碼
當(dāng)一個對象要?dú)w檔進(jìn)沙盒中時菱肖，就會調(diào)用這個方法
- (void)encodeWithCoder:(NSCoder *)encoder ;
[encoder encodeObject:self.xxx forKey:@"xxx"];
保存數(shù)據(jù)
[NSKeyedArchiver archiveRootObject:model toFile:JJTAccountPath];
模型寫代碼
當(dāng)從沙盒中解檔一個對象時（從沙盒中加載一個對象時），就會調(diào)用這個方法
- (id)initWithCoder:(NSCoder *)decoder；
if (self = [super init]) {
self.xxx = [decoder decodeObjectForKey:@"xxx"];
}
讀取數(shù)據(jù)
[NSKeyedUnarchiver unarchiveObjectWithFile:JJTAccountPath];
