UILabel自动适应尺寸

CGSize size = CGSizeMake(300, 1000);
CGSize labelSize = [self.introduction.text sizeWithFont:self.introduction.font constrainedToSize:size lineBreakMode:NSLineBreakByClipping];
self.introduction.frame = CGRectMake(self.introduction.frame.origin.x, self.introduction.frame.origin.y, labelSize.width, labelSize.height);

// introduction 就是一个label

UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(0, 100, 300, 100)];

label.numberOfLines = 0;

label.lineBreakMode = NSLineBreakByWordWrapping;

label.text = @"本店于十一期间特推出一系列优惠，限时限量敬请选购！<br>沙发：钻石品质，首领风范！<br>床垫：华贵典雅，彰显时尚！<br>尊贵而不失奢华，典雅却不失自然！温馨和浪漫的生活，我们与你一同创造!";

CGSize size = [label sizeThatFits:CGSizeMake(label.frame.size.width, MAXFLOAT)];

label.frame =CGRectMake(10, 100, 300, size.height);

label.font = [UIFont systemFontOfSize:14];

[self.view addSubview:label];