//NSString *dateStr=@"2012-05-17 11:23:23";
//转换后与NSString的时间相同
- (NSDate*) convertDateFromStringUTC:(NSString*)uiDate
{
NSDateFormatter *format=[[NSDateFormatter alloc] init];
[format setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSDate *fromdate=[format dateFromString:uiDate];
NSTimeZone *fromzone = [NSTimeZone systemTimeZone];
NSInteger frominterval = [fromzone secondsFromGMTForDate: fromdate];
NSDate *fromDate = [fromdate dateByAddingTimeInterval: frominterval];
return fromDate;
}