Object-C-Foundation-NSDate
NSDate 表达日期表达时间的方法
NSDate *now=[NSDate date]; 获得当前日期
NSDate *tomrrow=[now dateByAddingTimeInterval:24*60*60];
NSComparisonResulte result =[now compare:tomorrow];
if(result==NSOrderedAscending) 递增
NSOrderedDescending
日期处理
NSTimeInterval interval=[tomorrow timeIntervalSinceDate:now]时间差
NSLog(@"lf",interval);
NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
[formatter setDateFormat:@"yyyy年MM月dd日 HH:mm:ss"];
NSString *dateString =[formatter stringFromDate:now];
