===============>%.02f
NSString * string=@"34.627";
NSString *str =[NSString stringWithFormat:@"%.02f个",string.doubleValue];结果是34.63
===============>%.02f
NSString * string=@"34.627";
NSString *str =[NSString stringWithFormat:@"%.02f个",string.doubleValue];结果是34.63