UIDatepicker与NSDate的数据差异

Question

我有一个数据报警器，并以字符串格式将值保存到.plist文件中，其中键为UserDate。

来自datepicker的值以2013-02-13 11:17:34 +0000格式返回。

为了将其保存到.plist文件中，我需要将数据采集器转换为字符串2013-02-14T19:17:34Z。

在其他视图中，我希望从plist检索UserDate并与用户当前日期进行比较。我想要不同的日子和时间。

我将2012-02-12 19:17:34 +0800转换为destinationDate，并将其与NSDate new进行比较。我设法计算出两个日期之间的差额。但结果是不正确的。

如何获得iPhone和Datepicker的日期之间的两个日期的正确差异结果？我需要使用特定的时区吗？

Ex外信息：我住在GMT+8。我把模拟器设定为2012年2月13日，但结果仍然显示倒计时还有18小时零4分钟。

NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
int units = NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;

NSDateComponents *components = [calendar components:units fromDate:[NSDate date] toDate:destinationDate options:0];
[datelabel setText:[NSString stringWithFormat:@"%d%c %d%c %d%c %d%c %d%c", [components month], 'm', [components day], 
                    'd', [components hour], 'h', [components minute], 'm', [components second], 's']];

NSLog

​

​

编辑

Plist文件。

​

​

保存方法

NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
// get documents path
NSString *documentsPath = [paths objectAtIndex:0];
// get the path to our Data/plist file
NSString *plistPath = [documentsPath stringByAppendingPathComponent:@"Data.plist"];

// set the variables to the values in the text fields
self.userTitle = myTitle.text;
self.userMessage = myMessage.text;  

NSLog(@"METHOD SAVE");

NSLog(@"Datepicker value =  %@", myDate.date );

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
[dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss'Z'"];
NSString *mdate = [dateFormatter stringFromDate:myDate.date];
//  [dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss'Z'"];

NSLog(@"Converted from date picker, save into plist =  %@", mdate );

self.saveDate = mdate;
//self.userDate = myDate.date;

// create dictionary with values in UITextFields
NSDictionary *plistDict = [NSDictionary dictionaryWithObjects: [NSArray arrayWithObjects: userTitle, userMessage, saveDate, nil] forKeys:[NSArray arrayWithObjects: @"Title", @"Message", @"UserDate", nil]]; NSString *error = nil;
// create NSData from dictionary
NSData *plistData = [NSPropertyListSerialization dataFromPropertyList:plistDict format:NSPropertyListXMLFormat_v1_0 errorDescription:&error];

// check is plistData exists
if(plistData)
{
    // write plistData to our Data.plist file
    [plistData writeToFile:plistPath atomically:YES];
    
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success" message:@"Your settings have been saved." delegate:self cancelButtonTitle:nil otherButtonTitles:@"Ok",nil];
    [alert show];
}
else
{
    NSLog(@"Error in saveData: %@", error);
    //[error release];
}

viewWillAppear

- (void)viewWillAppear:(BOOL)animated {
[self.navigationController setNavigationBarHidden:YES];

[super viewWillAppear:animated];

// Data.plist code
// get paths from root direcory
NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
// get documents path
NSString *documentsPath = [paths objectAtIndex:0];
// get the path to our Data/plist file
NSString *plistPath = [documentsPath stringByAppendingPathComponent:@"Data.plist"];

// check to see if Data.plist exists in documents
if (![[NSFileManager defaultManager] fileExistsAtPath:plistPath])
{
    // if not in documents, get property list from main bundle
    plistPath = [[NSBundle mainBundle] pathForResource:@"Data" ofType:@"plist"];
}

// read property list into memory as an NSData object
NSData *plistXML = [[NSFileManager defaultManager] contentsAtPath:plistPath];
NSString *errorDesc = nil;
NSPropertyListFormat format;
// convert static property liost into dictionary object
NSDictionary *temp = (NSDictionary *)[NSPropertyListSerialization propertyListFromData:plistXML mutabilityOption:NSPropertyListMutableContainersAndLeaves format:&format errorDescription:&errorDesc];
if (!temp)
{
    NSLog(@"Error reading plist: %@, format: %d", errorDesc, format);
}

NSLog(@"Plist Title: %@", [temp objectForKey:@"Title"]);
NSLog(@"Plist Message: %@", [temp objectForKey:@"Message"]);
NSLog(@"Plist date: %@", [temp objectForKey:@"UserDate"]);

userTitle.text = [NSString localizedStringWithFormat:@"%@", [temp objectForKey:@"Title"]];
userMessage.text = [NSString localizedStringWithFormat:@"%@", [temp objectForKey:@"Message"]];

//http://stackoverflow.com/questions/1070354/how-do-i-get-the-current-date-in-cocoa

NSDate* now = [[NSDate alloc] initWithTimeIntervalSinceNow:3600];
userCoundown.text = [NSString stringWithFormat:@"%@",now];  

NSString *uDate = [[NSString alloc] init];
uDate = [temp objectForKey:@"UserDate"];
NSLog(@"Plist date in string - %@", uDate);

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
[dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss'Z'"];
NSDate *ddate = [dateFormatter dateFromString:uDate];
[dateFormatter setDateFormat:@"yyyy-MM-dd H:mm:ss Z"];

NSLog(@"Format date from Plist -  %@", [dateFormatter stringFromDate:ddate]);

//NSLog(@"GMT format from Plist - %@", timeStamp);

//http://www.epochconverter.com/#
destinationDate = ddate;
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(updateLabel) userInfo:nil repeats:YES];
}

更新标签

-(void)updateLabel {

NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
int units = NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;

NSDateComponents *components = [calendar components:units fromDate:[NSDate date] toDate:destinationDate options:0];
[datelabel setText:[NSString stringWithFormat:@"%d%c %d%c %d%c %d%c %d%c", [components month], 'm', [components day], 
                    'd', [components hour], 'h', [components minute], 'm', [components second], 's']];
}

Answer 1

NSDate在格林尼治时间内保持时间。如果您有时区，则必须指定它们。

这个问题还不清楚，所以这不是一个完整的答案，但是应该在plist中为NSDate提供一些帮助。

下面是一个用NSDate创建、编写和读取plist的示例

NSDictionary *plistDict = [NSDictionary dictionaryWithObjectsAndKeys:
                           userTitle,   @"Title",
                           userMessage, @"Message",
                           saveDate,    @"UserDate",
                           nil];

[plistDict writeToFile:filePath atomically:YES];

NSDictionary *plistDictRead = [NSDictionary dictionaryWithContentsOfFile:filePath];
NSDate *dateRead = [plistDictRead objectForKey:@"UserDate"];

不需要将NSDate转换为字符串，也不需要使用NSPropertyListSerialization。

Answer 2

记住创建NSDate，然后用有效时区和日历输出它！

查看我在另一篇文章中回答的类似问题：UIDatePicker return wrong NSDate