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];