将字符串转换为 NSDate

Question

我有一个“DateTimeArray”，该数组包含

DateTimeArray[index 0] = 20.05.2011 12:12:50    
DateTimeArray[index 1]=  20.05.2011 12:13:20   
DateTimeArray[index 2]=  20.05.2011 12:20:10  

字符串中的所有值，我想将此字符串转换为 NSDate 并且只想访问时间而不是日期
然后这次值将存储在数组中，这个新数组将用于绘制折线图

我希望有人知道这个问题

非常感谢

Answer 1

试试这个

NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:@"HH:mm:ss"];
NSDate *formattedDate = [df dateFromString:[DateTimeArray objectAtIndex:requiredIndex]];
[df release];

Answer 2

最佳和更简洁的方法：

NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:@"dd.MM.yyyy HH:mm:ss"];

for(int i=0; i < [DateTimeArray count]; ++i)
{
   NSString *string = [DateTimeArray objectAtIndex:i];
   NSDate *date = [df dateFromString:string];
   [timeArray addObject:time];
}

[df release]; // ALWAYS release unused objects

然后，为了仅访问几小时而不是几天，您应该选择每个 NSDate* 实例所需的组件：

// Get the Gregorian calendar
NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

// Get the date
NSDate* date = [timeArray objectAtIndex:my_index];

// Get the hours, minutes, seconds
NSDateComponents* hour = [cal components:NSHourCalendarUnit fromDate:date];
NSDateComponents* minute = [cal components:NSMinuteCalendarUnit fromDate:date];
NSDateComponents* second = [cal components:NSSecondCalendarUnit fromDate:date];

Answer 3

    NSMutableArray *nsdateArray = [NSMutableArray arrayWithCapacity:[DateTimeArray count]];
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@"dd.MM.yyyy HH:mm:ss"];

    for(NSString *currentString in DateTimeArray){
        NSDate *date = [dateFormat dateFromString:currentString];
        [nsdateArray addObject:date];
    }
    [dateFormat release];
    NSLog(@"ArrayWithDate:%@",[nsdateArray description]);

Answer 4

这是完整的代码集..希望它有所帮助..

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"HH:mm:ss"];
int i=0;//start for{} loop
NSString *currDate = [formatter dateFromString:[DateTimeArray objectAtIndex:i]];
[formatter release];

快乐 iCoding...

Answer 5

NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
[timeFormat setDateFormat:@"HH:mm:ss"]
NSString *theTime = [timeFormat dateFromString:date];
or
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(kCFCalendarUnitHour | kCFCalendarUnitMinute) fromDate:date];
NSInteger hour = [components hour];
NSInteger minute = [components minute];

Answer 6

代码如下，

for(int index=0;index<[DateTimeArray count];index++)
{
   NSDateFormatter *df = [[NSDateFormatter alloc] init];
   [df setDateFormat:@"HH:mm:ss"];
   NSString *timeString=[[[DateTimeArray objectAtIndex:index]componentsSeparatedByString:@" "]objectAtIndex:1];
   NSDate *time=[df dateFromString:timeString];
   [timeArray addObject:time];
   [df release];
}