UILabel and numberOfLines and sizeToFit:
This question already has an answer here:
I had a similar problem where -[UILabel sizeToFit] was not respecting the max width I set when numberOfLines was set to 2. Here's how I solved that problem:
CGFloat titleMaxWidth = 200;
CGFloat titleMinHeight = 30;
CGFloat titleMaxHeight = 40;
UILabel *titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 5, titleMaxWidth, titleMaxHeight)]; // alternatively, you could do this in a nib
titleLabel.numberOfLines = 0;
titleLabel.text = @"The title label will be sized appropriately with this technique.";
titleLabel.font = [UIFont boldSystemFontOfSize:16];
[titleLabel sizeToFit];
titleLabel.numberOfLines = 2;
if (titleLabel.height > titleMaxHeight)
{
titleLabel.height = titleMaxHeight;
}
else if (titleLabel.height < titleMinHeight)
{
titleLabel.height = titleMinHeight;
}
As you can see, I also wanted a minimum height for my label, as -sizeToFit often makes the label really small, but you could disregard that code if you don't care about a minimum height. The "magic number" of 40 for the titleMaxHeight comes from experimentation and finding out that a 2 line label with this font really only needs 40px. In this code, -sizeToFit is mainly used to keep the text within the width and determine whether the initial height of 40 can be reduced when we have a short string of text.
我使用了UIFont属性lineHeight：
CGFloat labelHeight = label.font.lineHeight*label.numberOfLines;