設置IOS的UILabel動態高度方法

 　　開始的時候按鈕事件中，可能寫的是這樣一段代碼：

　　if (isExpand) {

　　[lblBrief setNumberOfLines:2];

　　lblBrief.text = [StringUtil subString:strBrief AndSubLength:90];

　　[btnBrief setImage:[UIImage imageNamed:@"detailBriefDown"] forState:UIControlStateNormal];

　　[btnBrief setImage:[UIImage imageNamed:@"detailBriefDown"] forState:UIControlStateHighlighted];

　　}else{

　　[lblBrief setNumberOfLines:0];

　　lblBrief.text = strBrief;

　　[btnBrief setImage:[UIImage imageNamed:@"detailBriefUp"] forState:UIControlStateNormal];

　　[btnBrief setImage:[UIImage imageNamed:@"detailBriefUp"] forState:UIControlStateHighlighted];

　　}

　　可以通過setNumberOfLines:0,來讓概述的所以內容顯示出來，但如果，不計算所要顯示全部內容的總高度，label的寬高是不會自動增大的。

　　else{

　　[lblBrief setNumberOfLines:0];

　　lblBrief.text = strBrief;

　　CGSize constraint = CGSizeMake(self.view.frame.size.width - (15 * 2), 20000.0f);

　　CGSize size = [strBrief sizeWithFont:[UIFont systemFontOfSize:10]constrainedToSize:constraint lineBreakMode:UILineBreakModeWordWrap];

　　[brief setFrame:CGRectMake(15,160,size.width,size.height)];

　　[btnBrief setImage:[UIImage imageNamed:@"detailBriefUp"]forState:UIControlStateNormal];

　　[btnBrief setImage:[UIImage imageNamed:@"detailBriefUp"]forState:UIControlStateHighlighted];

　　}