根据要显示的文字以及UILable本身的字体，来计算能够完全显示所有文字的label所需要的大小，从而进行调整。

//Calculate the size necessary for the UILable  NSString *theText = @"Texting";  CGSize theStringSize = [theText sizeWithFont:font       constrainedToSize:theLabel.frame.size      lineBreakMode:theLabel.lineBreakMode];    //Adjust the size of the UILable  theLable.frame = CGRectMake(theLable.frame.origin.x,       theLable.frame.origin.y,       theStringSize.width, theStringSize.height);  theLable.text = theText;