处理日期时间NSDate

获取当前日期时间的代码如下：

    NSDate *dateToDay = [NSDate date];

    NSDateFormatter *df = [[NSDateFormatter alloc] init];

    [df setDateFormat:@"yyyy-MM-DD HH:mm:ss"];

    NSLocale *local = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];

    [df setLocale:local];

    NSString *myDataString = @"2009-09-15 18:30:00";

从字符串生成日期对象的代码如下：

NSDate *myData = [df dateFromString:myDataString];

日期比较的代码如下：

    switch ([dateToDay compare:myData]) {

        case NSOrderedSame:

            NSLog(@"These dates are the same!");

            break;

        case NSOrderedAscending:

            NSLog(@"dateToDay is earlier than myDate!");

            break;

        case NSOrderedDescending:

            NSLog(@"mydate is earlier than dateToDay");

            break;

        default:

            NSLog(@"Bad times. Invalid enum value returned.");

            break;

    }

注意：掌握NSDate和NSString相互之间的转换。

完整代码如下：

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])

{

    NSDate *dateToDay = [NSDate date];

    NSDateFormatter *df = [[NSDateFormatter alloc] init];

    [df setDateFormat:@"yyyy-MM-DD HH:mm:ss"];

    NSLocale *local = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];

    [df setLocale:local];

    NSString *myDataString = @"2009-09-15 18:30:00";

    NSDate *myData = [df dateFromString:myDataString];

    switch ([dateToDay compare:myData]) {

        case NSOrderedSame:

            NSLog(@"These dates are the same!");

            break;

        case NSOrderedAscending:

            NSLog(@"dateToDay is earlier than myDate!");

            break;

        case NSOrderedDescending:

            NSLog(@"mydate is earlier than dateToDay");

            break;

        default:

            NSLog(@"Bad times. Invalid enum value returned.");

            break;

    }

    return ;

}

NSData转换为NSString的代码如下：

    NSMutableData *data;

    NSString *tmpdata = [[NSString alloc] initWithString:data encoding:NSASCIIStringEncoding];

    NSLog(@"[***] DATA:%@" , tmpdata);

    [tmpdata release];

NSString转换为NSData的代码如下：

    NSString *str = @"teststring";

    NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];

巴特西

处理日期时间NSDate

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