Iphone 如何从约会中减去30分钟

我正在获取日期值日期：2013-06-07 18:30:00+0000。我正试图从中减去30分钟，但它没有给出适当的时间

我试过这个

 NSTimeInterval secondsPerHour = 60*30;
 NSDate *newDate = [date dateByAddingTimeInterval:-secondsPerHour];

你可以试试，像这样的：

NSDate* yourDate = [NSDate dateWithTimeIntervalSinceNow:0]; // your date, to substract 30 mins

NSDateComponents *dc = [[NSCalendar currentCalendar] components:(NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit |  NSHourCalendarUnit | NSMinuteCalendarUnit) fromDate:yourDate];
[dc setMinute:[dc minute] - 30];

NSDate* date  = [[NSCalendar currentCalendar] dateFromComponents:dc]; // 30 mins before now

或者：

NSDate* yourDate = [NSDate dateWithTimeIntervalSinceNow:0]; // your date, to substract 30 mins

NSDateComponents *components = [[NSDateComponents alloc] init];
[components setMinute:-30];

NSDate* date  = [[NSCalendar currentCalendar] dateByAddingComponents:components toDate:yourDate options:0]; // 30 mins before now

您可以使用：

NSDate *minusOneHr = [[NSDate date] dateByAddingTimeInterval:-30*60];

---

原因：无符号整数的

负数

是一个

正数

。这应该起作用：

NSDate *newDate = [date dateByAddingTimeInterval:-(NSTimeInterval)((u_int32_t)30*60)];

编辑：可选使用

NSDateComponents

NSDateComponents *dateComponents = [[NSDateComponents alloc] init];
[dateComponents setMinute:-30];
NSDate *halfHourAgo = [[NSCalendar currentCalendar] dateByAddingComponents:dateComponents toDate:yourDateHere options:0];
NSLog(@"\ncurrentDate: %@ \n halfHourAgo: %@", yourDateHere, halfHourAgo);

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在viewDidLoad中复制粘贴此代码并首先检查结果

NSDate *today = [[NSDate alloc] init];
    NSLog(@"Today %@", today);
    NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
    [offsetComponents setMinute:-30]; // If you want to change Month,Year,Day,Hour etc. Just change the "setMinute" to setMonth,setYear,setDay,setHour
    NSDate *dateComp = [gregorian dateByAddingComponents:offsetComponents toDate:today options:0];
    NSLog(@"Desired Day %@", dateComp);

斯威夫特5

let minus30Min = Date().addingTimeInterval(-30 * 60)

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我认为这与问题中给出的代码相同。只需切换数值的位置仔细阅读问题，然后发表评论，用户希望减去分钟数，因此它不取决于月内有多少天低于tofa？？？？？

let minus30Min = Date().addingTimeInterval(-30 * 60)