动态计算Label高度

//1.设置该label的numberOfLines为0

self.titleLabel.numberOfLines = 0;

//2.字体的设置要与之前相同

NSDictionary * attribute = @{NSFontAttributeName:[UIFont systemFontOfSize:17]};

//3.将size的高度设为最大值

CGSize size = CGSizeMake(355, CGFLOAT_MAX);

//4.将label的高度设为动态计算出的size的高度

size = [news.title boundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOrigin attributes:attribute context:nil].size;

self.titleLabel.frame = CGRectMake(10, 0, 355, size.height);