UIFont *cellFont = [UIFont systemFontOfSize:LEARN_TITLE_FONT15];
CGSize constraintSize = CGSizeMake(260, MAXFLOAT);
CGSize labelSize=[str sizeWithFont:cellFont constrainedToSize:constraintSize lineBreakMode:UILineBreakModeWordWrap];
detailLabel.frame = CGRectMake(15, 20, labelSize.width, labelSize.height);
[detailLabel setText:str WithFont:[UIFont systemFontOfSize:LEARN_TITLE_FONT15] AndColor:UIColorRGB(0X333333)];