//初始化label
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0,0,0,0)];
//设置自动行数与字符换行
[label setNumberOfLines:0];
label.lineBreakMode = UILineBreakModeWordWrap;
// 测试字串 NSString *s = @"这是一个测试！！！";
UIFont *font = [UIFont fontWithName:@"Arial" size:12];
//设置一个行高上限
CGSize size = CGSizeMake(320,2000);
//计算实际frame大小，并将label的frame变成实际大小 CGSize labelsize = [s sizeWithFont:font constrainedToSize:size lineBreakMode:UILineBreakModeWordWrap]; [label setFrame:CGRectMake:(0,0, labelsize.width, labelsize.height)];