xcode iPhone：从日期选择器获取日期
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iPhone: Getting date from date picker
提问by Henry F
I wrote an app that allows users to enter in a date on a date picker, and the app will alert the user 36 hours before that date arrives. My issue is in the dateFromString:. I'm not sure what to put in there. Here is the code:
我编写了一个应用程序，允许用户在日期选择器上输入日期，该应用程序会在该日期到来前 36 小时提醒用户。我的问题在dateFromString:. 我不确定要在那里放什么。这是代码：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
UILocalNotification *localNotif = [[UILocalNotification alloc] init];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"mm'/'dd'/'yyyy"];
NSDate *eventDate=[dateFormatter dateFromString: ];
localNotif.fireDate = [eventDate dateByAddingTimeInterval:-13*60*60];
localNotif.timeZone = [NSTimeZone defaultTimeZone];
localNotif.alertBody = @"Event tommorow!";
localNotif.alertAction = nil;
localNotif.soundName = UILocalNotificationDefaultSoundName;
localNotif.applicationIconBadgeNumber = 0;
[[UIApplication sharedApplication]presentLocalNotificationNow:localNotif];
return YES;
}
}
Any help is much appreciated, thank you!
非常感谢任何帮助，谢谢！
Edit: Here is some additional code that I'm using to save the date they entered on the date picker if that helps:
编辑：这是我用来保存他们在日期选择器上输入的日期的一些附加代码，如果有帮助的话：
- (void)viewDidLoad {
NSDate *storedDate = [[NSUserDefaults standardUserDefaults] objectForKey:@"DatePickerViewController.selectedDate"];
[self.datePicker setDate:storedDate animated:NO];
}
And this is the method that saves the data:
这是保存数据的方法：
- (IBAction)dateChanged:(id)sender {
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSDate *selectedDate = [self.datePicker date];
[defaults setObject:selectedDate forKey:@"DatePickerViewController.selectedDate"];}
回答by Pavel Oganesyan
Why do you need a string? After making
为什么需要字符串？制作后
[defaults setObject:selectedDate forKey:@"DatePickerViewController.selectedDate"];
[defaults setObject:selectedDate forKey:@"DatePickerViewController.selectedDate"];
you can access your date just like
你可以像访问你的日期一样
NSDate* eventDate = [[NSUserDefaults standardUserDefaults] objectForKey:@"DatePickerViewController.selectedDate"];
Using strings is not so nice with date - you should care about locale and time formats (12 hours or 24 hours) etc.
使用字符串对日期不太好 - 您应该关心语言环境和时间格式（12 小时或 24 小时）等。
