Objective-C和sqlite的DATETIME类型 [英] Objective-C and sqlite's DATETIME type

问题描述

我有一个sqlite3表，试图将其映射到Objective-C中的对象.该表的一个属性是"completed_at"，该属性存储为DATETIME.

I have a sqlite3 table that I'm trying to map to an object in objective-C. One attribute of the table is 'completed_at' which is stored as a DATETIME.

我想在我的Objective-C类(继承自NSObject)上创建一个属性，该属性将很好地映射到'completed_at'属性.

I want to create a property on my objective-C class (which inherits from NSObject) that will map well to the 'completed_at' attribute.

Objective-C具有NSDate类型，但是我不确定是否可以直接映射?

Objective-C has an NSDate type but I'm not sure if that will map directly?

推荐答案

我在这里仅分享有关日期格式的核心内容，以保存和检索要显示的数据.如果您对此代码段有任何疑问，那么我将分享我在项目中使用的完整代码.

I am sharing here just the core things regarding date formatting for saving and retrieving the data for presentation. If you have any problem with this code snippet then I will share the full code that I used for my project.

保存数据时，请按照以下方式将日期值绑定到sql语句中:

When you save your data, bind your date value in the sql statement like this way:

    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSString *dateString=[dateFormat stringFromDate:[NSDate date]];

    sqlite3_bind_text(saveStmt, 1, [dateString UTF8String] , -1, SQLITE_TRANSIENT);

当您检索数据时，您必须编写以下代码:

and when you retrieve data you have to write this code:

    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *myDate =[dateFormat dateFromString:[NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 1)]];

现在您有了一个NSDate类型的变量myDate，可以用自己的方式呈现它:

now you have a variable myDate of NSDate type which you can render in your way:

    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"dd-MM-yyyy hh:mm:ss a"];
    NSLog(@"My Date was : %@", [formatter stringFromDate:myDate]);

您必须记住三件事:

1. 在您的SQLite日期字段中，类型应为DATETIME
2. 存储和检索时的日期格式应该相同
3. 现在，您可以按照自己的方式显示，但要遵循格式.下面是格式详细信息.

格式:

   'dd' = Day 01-31
   'MM' = Month 01-12
   'yyyy' = Year 2000
   'HH' = Hour in 24 hour
   'hh' = Hour in 12 hour
   'mm' = Minute 00-59
   'ss' = Second 00-59
   'a' = AM / PM

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