draw only top, right, and bottom border around a uilabel

问题

i try to add border for a uilabel, but i only want to have top, right, and bottom border.

like this

           ----------------
                          |
            I am a label  |
                          |
           ----------------

I try to use these codes, but it adds all 4 sides by default

    myLabel.layer.borderWidth = 1;
    myLabel.layer.borderColor = [UIColor blackColor];

Is that anyway i can only add 3 sides, or even 1 or 2 sides?

Thanks!

回答1:

You can use a mask. This is the code I used to test the theory, and it works well:

// Define the border width in a variable, we'll be using it elsewhere
CGFloat borderWidth = 1.0;

// This creates a testing view to test the theory, in your case this will be your UILabel
UIView* view = [[UIView alloc] initWithFrame:CGRectMake(20, 60, 250, 100)];
view.layer.borderColor = [UIColor blackColor].CGColor;
view.layer.borderWidth = borderWidth;
[self.view addSubview:view];

// Create the mask to cover the area of the view you want to **show**
// Here, we create a mask that covers most of the view, except the left edge
// The mask needs to be coloured in black, as black acts as transparent, whereas white is opaque in mask parlance
UIView* mask = [[UIView alloc] initWithFrame:CGRectMake(borderWidth, 0, view.frame.size.width - borderWidth, view.frame.size.height)];
mask.backgroundColor = [UIColor blackColor];
view.layer.mask = mask.layer;

You can adjust the size and position of the mask (given the borderWidth) to show/hide the border edges you're interested in. The example above hides the left edge.

回答2:

You'll have to adjust sizes but this is the gist of it. (might be some typos)

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 35)];
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10, 15, 320, 20)];

CALayer *bottomBorder = [CALayer layer];
bottomBorder.frame = CGRectMake(0, 40, 320, .5);

CALayer *rightBorder = [CALayer layer];
rightBorder.frame = CGRectMake(320, 0, 40, .5);

CALayer *topBorder = [CALayer layer];
topBorder.frame = CGRectMake(0, 0, 320, .5);

[view.layer addSublayer:bottomBorder];
[view.layer addSublayer:topBorder];
[view.layer addSublayer:rightBorder];
[view.layer addSublayer:label];

回答3:

You can draw your three sides with one line by creating a CALayer that uses a UIBezierPath. With all of the examples, include the QuartzCore framework as part of your project.

Following your original code as a starting point:

// at the top of the file with this code, include:
#import <QuartzCore/QuartzCore.h>

CGRect rect = myLabel.frame;

UIBezierPath * linePath = [UIBezierPath bezierPath];

// start at top left corner
[linePath moveToPoint:CGPointMake(0,0);
// draw top line across
[linePath addLineToPoint:CGPointMake(rect.size.width, 0);
// draw right vertical side
[linePath addLineToPoint:CGPointMake(rect.size.width, rect.size.height);
// draw left vertical side
[linePath addLineToPoint:CGPointMake(0, rect.size.height);

// draw from bottom right corner back to bottom left corner
[linePath addLineToPoint:CGPointMake(0, rect.size.height);

// create a layer that uses your defined path
CAShapeLayer * lineLayer = [CAShapeLayer layer];
lineLayer.lineWidth = 1.0;
lineLayer.strokeColor = [UIColor blackColor].CGColor;

lineLayer.fillColor = nil;
lineLayer.path = linePath.CGPath;

[myLabel.layer addSublayer:lineLayer];

回答4:

I'm using Swift 3.

// myLabel is a UILabel
let frame = myLabel.frame //Frame of label

// Bottom Layer
let bottomLayer = CALayer()
bottomLayer.frame = CGRect(x: 0, y: frame.height - 1, width: frame.width, height: 1)
bottomLayer.backgroundColor = UIColor.black.cgColor
myLabel.layer.addSublayer(bottomLayer)

// Top Layer
let topLayer = CALayer()
topLayer.frame = CGRect(x: 0, y: 0, width: frame.width, height: 1)
topLayer.backgroundColor = UIColor.black.cgColor
myLabel.layer.addSublayer(topLayer)

Similarly:

// Right Layer
let rightLayer = CALayer()
rightLayer.frame = CGRect(x: frame.width - 1, y: 0, width: 1, height: frame.height)
rightLayer.backgroundColor = UIColor.black.cgColor
myLabel.layer.addSublayer(rightLayer)

Where 1 is the width of the border.

回答5:

Here you guys go! Hope this helps, Add this inside UItextfield override class

UIView *view = [[UIView alloc] init];
view.translatesAutoresizingMaskIntoConstraints = NO;
view.layer.borderWidth = 1;
view.backgroundColor = [UIColor blackColor];
[self addSubview:view];

[self addConstraint:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeBottom multiplier:1.0 constant:0.0]];
[self addConstraint:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0.0]];
[self addConstraint:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeHeight multiplier:1.0 constant:1.0]];
[self addConstraint:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:1.0]];

回答6:

Thanks @jaiswal, i used your code and created a function, because i had more than 10 UILabels. I have put it here for reference.

 func buttomBoarder(label: UILabel) -> UILabel {
    let frame = label.frame

    let bottomLayer = CALayer()
    bottomLayer.frame = CGRect(x: 0, y: frame.height - 1, width: frame.width, height: 1)
    bottomLayer.backgroundColor = UIColor.black.cgColor
    label.layer.addSublayer(bottomLayer)

    return label

}

Called using

labelName = buttomBoarder(label: labelName)

回答7:

You can subclass UILabel and override drawRect: to do that.

Or you could just make 3 UIView's with black background as subviews of this label. If you set autoresizingMask on them properly they will adjust to changes in the size of the label. Top border should have flexible width and flexible bottom margin, bottom border should have flexible width and flexible top margin, right border should have flexible height and flexible left margin.

回答8:

You can do it with multiple ways: 1st one is the easiest one just find a image that looks like your border strokes. Then add it an UIImageView back of your UILabel. 2nd way is override UILabel drawRect: then draw the stoke according to your needs.

来源：https://stackoverflow.com/questions/21586089/draw-only-top-right-and-bottom-border-around-a-uilabel

标签

ios

uilabel