Question

我现在感到很茫然，我似乎无法弄清楚为什么我的简单if / else语句会破坏我的for循环。这两种方法可以保存和读取plist中的数据。评论文本被评论时，一切正常。取消注释后，数据无法保存（或无法正确读取）。

编辑：更新下面的代码后删除[NSNull null]（更新的代码可以在下面看到），我仍然有完全相同的问题。有什么想法吗？

此外，＆＃34; tab＆＃34;是一个NSMutableArray。

- (void)saveDataToFile
{ 
// translate objects in to an nsarray that contains dictionaries so we can write

NSMutableArray *a = [NSMutableArray array];
for (int c = 0; c < [self.employeeList count]; c++) {
    NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];
    id r = [self.employeeList objectAtIndex:c];
    [dictionary setObject:[r username] forKey:@"username"];
    [dictionary setObject:[r passWord] forKey:@"passWord"];
    [dictionary setObject:[r employeeName] forKey:@"employeeName"];
    [dictionary setObject:[r email] forKey:@"email"];
    [dictionary setObject:[r phone] forKey:@"phone"];
    [dictionary setObject:[r hours] forKey:@"hours"];
//        if ([r tab] != nil) {
//        [dictionary setObject:[r tab] forKey:@"tab"];
//    }
    [dictionary setValue:[NSNumber numberWithFloat:[r tabTotal]] forKey:@"tabTotal"];
    [a addObject:dictionary];

    }

[a writeToFile:[self dataFileName] atomically:YES];
}

- (void)readDataFromFile
{
[self createEmployeeList];
NSArray *tempArray = [NSArray arrayWithContentsOfFile:[self dataFileName]];
for (int d = 0; d < [tempArray count]; d++) {
    Employee *person = [[Employee alloc] init];
    NSDictionary *dict = [tempArray objectAtIndex:d];
    [person setUsername:[dict objectForKey:@"username"]];
    [person setPassWord:[dict objectForKey:@"passWord"]];
    [person setEmployeeName:[dict objectForKey:@"employeeName"]];
    [person setEmail:[dict objectForKey:@"email"]];
    [person setPhone:[dict objectForKey:@"phone"]];
    [person setHours:[dict objectForKey:@"hours"]];
//        if ([dict objectForKey:@"tab"] == nil)  {
//            NSMutableArray *array = [[NSMutableArray alloc] init];
//            [person setTab:array];
//        }else {
//            [person setTab:[dict objectForKey:@"tab"]];
//        }

    [person setTabTotal:[[dict valueForKey:@"tabTotal"] floatValue]];

    [self.employeeList addObject:person];
    }


}

Answer 1

您无法将NSNull值保存到字典文件中。你只能拥有一组有限的类型，比如NSString，NSNumber，NSArray，NSDictionary。

保存时，不要将值设置为NSNull，也不要设置它。

阅读时，如果objectForKey:返回nil，则表示没有设置此类密钥。

如果确实想要存储NSNull值，请看一下：How to serialize a NSDictionary/NSArray/Property List (plist) which contains NSNull。

如果/ Else Statment Breaking for-loop

1 个答案: