How to align UILabel text from bottom?

问题

How the UILabel can be aligned from bottom. Let say, my label can hold three line of text.If the input text is single line, then this line should come bottom of the label.Please refer the below image for better understanding. The orange area is the full frame of label.Currently it has one line and it is aligned center. So what I want is, it should always aligned bottom regardless of how many lines.

Please suggest your ideas.

Thank you.

回答1:

Here are two ways of doing that...

1. First set numberOfLines to 0 and then use sizeToFit property of UILabel so your UILabel display with its contentSize.

yourLabel.numberOfLines = 0;

[yourLabel sizeToFit];

See more information from this link: Vertically align text within a UILabel

2. Another option is to take UITextField instead of UILabel and set userInteractionEnabled to NO like below...

[yourTextField setUserInteractionEnabled:NO];

and then set the contentVerticalAlignment property to bottom like below...

[yourTextField setContentVerticalAlignment:UIControlContentVerticalAlignmentBottom];

UPDATE

Also, with UITextField, we can't achieve multiple lines. So instead we can use UITextView and set its userInteractionEnabled to NO. Then, use the code below to make it bottom aligned.

CGFloat topCorrect = ([label bounds].size.height - [label contentSize].height);
topCorrect = (topCorrect <0.0 ? 0.0 : topCorrect);
label.contentOffset = (CGPoint){.x = 0, .y = -topCorrect};

回答2:

Subclass UILabel

@interface Label : UILabel

@end

Then override drawTextInRect like so

@implementation Label

- (void)drawTextInRect:(CGRect)rect
{
    if(alignment == top) {

        rect.size.height = [self sizeThatFits:rect.size].height;
    }

    if(alignment == bottom) {

        CGFloat height = [self sizeThatFits:rect.size].height;

        rect.origin.y += rect.size.height - height;
        rect.size.height = height;
    }

    [super drawTextInRect:rect];
}

@end

回答3:

Swift 4.2 version using the contentMode property to set top and bottom:

class VerticalAlignedLabel: UILabel {

    override func drawText(in rect: CGRect) {
        var newRect = rect
        switch contentMode {
        case .top:
            newRect.size.height = sizeThatFits(rect.size).height
        case .bottom:
            let height = sizeThatFits(rect.size).height
            newRect.origin.y += rect.size.height - height
            newRect.size.height = height
        default:
            ()
        }

        super.drawText(in: newRect)
    }
}

Then setup your label like that:

let label: VerticalAlignedLabel = UILabel()
label.contentMode = .bottom

回答4:

i only set a bottom constraint to the super view in IB which works for me without using code and also number of Lines for a maximum constraint.

回答5:

I had the same issue. Here is how I made to align the text to the bottom of my UILabel:

- (void)alignLabel:(UILabel *)l withText:(NSString *)text verticalAlignOption:(int)vertAlign{
CGSize stringSize = [text sizeWithFont:l.font constrainedToSize:l.frame.size lineBreakMode:l.lineBreakMode];

switch (vertAlign) {
    case 0: // align = top
        l.frame = CGRectMake(l.frame.origin.x,
                                   l.frame.origin.y,
                                   l.frame.size.width,
                                   stringSize.height
                                   );
        break;
    case 1: // align = bottom
        l.frame = CGRectMake(l.frame.origin.x,
                                   (l.frame.origin.y + l.frame.size.height) - stringSize.height,
                                   l.frame.size.width,
                                   stringSize.height
                                   );
        break;
    case 2: // align = middle
        // default
        break;
}

l.text = text;
}

Ahd you simple call the method like this to align to the bottom:

[self alignLabel:self.mediaTitle withText:@"My text to align" verticalAlignOption:1];

回答6:

Another option: use one label for your background color, I call this one originalLabel, and another for the text, called textLabel in my example. Then calculate the height and Y coordinate for textLabel:

[textLabel sizeToFit];
int height = textLabel.frame.size.height;
int yCoord = originalLabel.frame.origin.y + 
          originalLabel.frame.size.height - height;
textLabel.frame = CGRectMake( originalLabel.frame.origin.x, yCoord,
          textLabel.frame.size.width, height);

回答7:

In IB as @Tobe said Bottom constraint to superview should work, Incase if you have multiple subview or horizontal stack view with one element to have bottom constraint then use Layout Margin to be Fixed with bottom less than other margins