聊天两边的窗口高度的设置

UILabel *left = [[UILabel alloc] init];

    left.text = @" Sent when the application is about to move from active to inactive state.";

    left.backgroundColor = [UIColor blueColor];

    //每个label宽200
    UIFont *font = left.font;
    NSString *content = left.text;

    CGSize realSize = [content sizeWithFont:font constrainedToSize:CGSizeMake(200, 1000)];

    left.frame = CGRectMake(10, 30, realSize.width, realSize.height);
    left.numberOfLines = 0;
    left.layer.cornerRadius = 10;
    left.clipsToBounds = YES;
    [self.window addSubview:left];

    UILabel *right = [[UILabel  alloc] init];

    right.text = @"Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates";

    right.backgroundColor  = [UIColor redColor];
    //计算高度,宽度200
    font = right.font;
    content = right.text;

    realSize = [content sizeWithFont:font constrainedToSize:CGSizeMake(200, 1000)];

    CGFloat leftMaxY = CGRectGetMaxY(left.frame);

    right.frame = CGRectMake(320 - realSize.width - 10, leftMaxY + 20, realSize.width, realSize.height);

    right.numberOfLines = 0;

    right.layer.cornerRadius = 10;
    right.clipsToBounds = YES;

    [self.window addSubview:right];