ios - 你如何以编程方式从视图控制器中画一条线？

Question

我有一个UIViewController. 如何在其以编程方式创建的视图之一中画一条线？

Answer 1

有两种常见的技术。

1. 使用CAShapeLayer：

   • 创建一个UIBezierPath（用任何你想要的替换坐标）：

     UIBezierPath *path = [UIBezierPath bezierPath];
     [path moveToPoint:CGPointMake(10.0, 10.0)];
     [path addLineToPoint:CGPointMake(100.0, 100.0)];
     

   • 创建一个CAShapeLayer使用它的UIBezierPath：

     CAShapeLayer *shapeLayer = [CAShapeLayer layer];
     shapeLayer.path = [path CGPath];
     shapeLayer.strokeColor = [[UIColor blueColor] CGColor];
     shapeLayer.lineWidth = 3.0;
     shapeLayer.fillColor = [[UIColor clearColor] CGColor];
     

   • 将其添加CAShapeLayer到您的视图层：

     [self.view.layer addSublayer:shapeLayer];
     

   在以前版本的 Xcode 中，您必须手动将QuartzCore.framework 添加到项目的“Link Binary with Libraries”并在 .m 文件中导入<QuartzCore/QuartzCore.h>标头，但这不再需要（如果您有“Enable Modules”和“Link自动框架”构建设置已打开）。

2. 另一种方法是子类化UIView，然后在方法中使用CoreGraphics调用drawRect：

   • 创建一个UIView子类并定义一个drawRect画线的子类。

     你可以用核心图形做到这一点：

     - (void)drawRect:(CGRect)rect {
         CGContextRef context = UIGraphicsGetCurrentContext();
     
         CGContextSetStrokeColorWithColor(context, [[UIColor blueColor] CGColor]);
         CGContextSetLineWidth(context, 3.0);
         CGContextMoveToPoint(context, 10.0, 10.0);
         CGContextAddLineToPoint(context, 100.0, 100.0);
         CGContextDrawPath(context, kCGPathStroke);
     }
     

     或使用UIKit：

     - (void)drawRect:(CGRect)rect {
         UIBezierPath *path = [UIBezierPath bezierPath];
         [path moveToPoint:CGPointMake(10.0, 10.0)];
         [path addLineToPoint:CGPointMake(100.0, 100.0)];
         path.lineWidth = 3;
         [[UIColor blueColor] setStroke];
         [path stroke];
     }
     

   • 然后你可以使用这个视图类作为你的NIB/故事板或视图的基类，或者你可以让你的视图控制器以编程方式将它添加为子视图：

     PathView *pathView = [[PathView alloc] initWithFrame:self.view.bounds];
     pathView.backgroundColor = [UIColor clearColor];
     
     [self.view addSubview: pathView];
     

---

上述两种方法的 Swift 版本如下：

1. CAShapeLayer：

   // create path
   
   let path = UIBezierPath()
   path.move(to: CGPoint(x: 10, y: 10))
   path.addLine(to: CGPoint(x: 100, y: 100))
   
   // Create a `CAShapeLayer` that uses that `UIBezierPath`:
   
   let shapeLayer = CAShapeLayer()
   shapeLayer.path = path.cgPath
   shapeLayer.strokeColor = UIColor.blue.cgColor
   shapeLayer.fillColor = UIColor.clear.cgColor
   shapeLayer.lineWidth = 3
   
   // Add that `CAShapeLayer` to your view's layer:
   
   view.layer.addSublayer(shapeLayer)
   

2. UIView子类：

   class PathView: UIView {
   
       var path: UIBezierPath?           { didSet { setNeedsDisplay() } }
       var pathColor: UIColor = .blue    { didSet { setNeedsDisplay() } }
   
       override func draw(_ rect: CGRect) {
           // stroke the path
   
           pathColor.setStroke()
           path?.stroke()
       }
   
   }
   

   并将其添加到您的视图层次结构中：

   let pathView = PathView()
   pathView.translatesAutoresizingMaskIntoConstraints = false
   view.addSubview(pathView)
   
   NSLayoutConstraint.activate([
       pathView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
       pathView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
       pathView.topAnchor.constraint(equalTo: view.topAnchor),
       pathView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
   ])
   
   pathView.backgroundColor = .clear
   
   let path = UIBezierPath()
   path.move(to: CGPoint(x: 10, y: 10))
   path.addLine(to: CGPoint(x: 100, y: 100))
   path.lineWidth = 3
   
   pathView.path = path
   

   上面，我是以PathView编程方式添加的，但您也可以通过 IB 添加它，只需以path编程方式设置它。

Answer 2

创建一个 UIView 并将其添加为视图控制器视图的子视图。您可以将此子视图的高度或宽度修改为非常小，使其看起来像一条线。如果需要绘制对角线，可以修改子视图的变换属性。

例如画黑色水平线。这是从您的视图控制器的实现中调用的

UIView *lineView = [[UIView alloc] initWithFrame:CGRectMake(0,0, self.view.frame.size.width, 1)];
lineView.backgroundColor = [UIColor blackColor];
[self.view addSubview:lineView];

Answer 3

这里有一个很酷的技术，你可能会觉得有用：Using blocks for drawing to Avoid subclassing in Objective-C

在您的项目中包含本文的通用视图子类，然后您可以将这种代码放入视图控制器中，以动态创建绘制一条线的视图：

DrawView* drawableView = [[[DrawView alloc] initWithFrame:CGRectMake(0,0,320,50)] autorelease];
drawableView.drawBlock = ^(UIView* v,CGContextRef context)
{
  CGPoint startPoint = CGPointMake(0,v.bounds.size.height-1);
  CGPoint endPoint = CGPointMake(v.bounds.size.width,v.bounds.size.height-1);

  CGContextSetStrokeColorWithColor(context, [UIColor grayColor].CGColor);
  CGContextSetLineWidth(context, 1);
  CGContextMoveToPoint(context, startPoint.x + 0.5, startPoint.y + 0.5);
  CGContextAddLineToPoint(context, endPoint.x + 0.5, endPoint.y + 0.5);
  CGContextStrokePath(context);
};
[self.view addSubview:drawableView];

Answer 4

斯威夫特 3：

let path = UIBezierPath()
path.move(to: CGPoint(x: 10, y: 10))
path.addLine(to: CGPoint(x: 100, y: 100))

let shapeLayer = CAShapeLayer()
shapeLayer.path = path.cgPath
shapeLayer.strokeColor = UIColor.blue.cgColor
shapeLayer.lineWidth = 3.0

view.layer.addSublayer(shapeLayer)

Answer 5

你可以使用 UIImageView 在上面画线。

但是，它允许跳过子分类。而且由于我不太倾向于 Core Graphics 仍然可以使用它。你可以把它放进去——ViewDidLoad

  UIGraphicsBeginImageContext(self.view.frame.size);
  [self.myImageView.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
  CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
  CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush);

  CGContextMoveToPoint(UIGraphicsGetCurrentContext(), 50, 50);
  CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), 200, 200);
  CGContextStrokePath(UIGraphicsGetCurrentContext());
  CGContextFlush(UIGraphicsGetCurrentContext());
  self.myImageView.image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();

除了 Rob 的回答，第三种方法是使用UIImageView- 掩盖它 - xib 的视图。（这是在 xcode 5 中的 xib 上拖动时的默认 UIImageView 外观）

干杯和+1！

Answer 6

你不应该真的，但如果出于某种原因它对你有意义，你可以创建一个 UIView 的子类，DelegateDrawView例如，它需要一个实现类似方法的委托

- (void)delegateDrawView:(DelegateDrawView *)aDelegateDrawView drawRect:(NSRect)dirtyRect

然后在方法中 -[DelegateDrawView drawRect:]你应该调用你的委托方法。

但是为什么要将视图代码放在控制器中。

你最好创建一个 UIView 的子类，在它的两个角之间画一条线，你可以有一个属性来设置哪两个，然后将视图从视图控制器定位到你想要的位置。

Answer 7

在您的视图中绘制非常简单，@Mr.ROB 说两种方法我采用了第一种方法。

只需将代码复制粘贴到你们想要的地方。

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [[event allTouches] anyObject];
     startingPoint = [touch locationInView:self.view];

    NSLog(@"Touch starting point = x : %f Touch Starting Point = y : %f", touchPoint.x, touchPoint.y);
}
-(void)touchesCancelled:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{

}
-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [[event allTouches] anyObject];
     touchPoint = [touch locationInView:self.view];

    NSLog(@"Touch end point =x : %f Touch end point =y : %f", touchPoint.x, touchPoint.y);
}
-(void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{

    UITouch *touch = [[event allTouches] anyObject];
    touchPoint = [touch locationInView:self.view];
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(touchPoint.x,touchPoint.y)];
    [path addLineToPoint:CGPointMake(startingPoint.x,startingPoint.y)];
    startingPoint=touchPoint;
    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    shapeLayer.path = [path CGPath];
    shapeLayer.strokeColor = [[UIColor blueColor] CGColor];
    shapeLayer.lineWidth = 3.0;
    shapeLayer.fillColor = [[UIColor redColor] CGColor];
    [self.view.layer addSublayer:shapeLayer];

    NSLog(@"Touch moving point =x : %f Touch moving point =y : %f", touchPoint.x, touchPoint.y);
    [self.view setNeedsDisplay];


}
- (void)tapGestureRecognizer:(UIGestureRecognizer *)recognizer {
    CGPoint tappedPoint = [recognizer locationInView:self.view];
    CGFloat xCoordinate = tappedPoint.x;
    CGFloat yCoordinate = tappedPoint.y;

    NSLog(@"Touch Using UITapGestureRecognizer x : %f y : %f", xCoordinate, yCoordinate);
}

它会像一条线一样绘制，手指移动的地方

Answer 8

斯威夫特 5.4

使用高度为 1 或 2 点的 UIView 并将其添加为视图控制器视图的子视图。

class Separator: UIView {

    let line = UIView()

    override init(frame: CGRect) {
        super.init(frame: frame)
        configure()
    }


    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    private func configure() {
        backgroundColor = .red

        addSubview(line)
        line.translatesAutoresizingMaskIntoConstraints = false
        line.backgroundColor = .secondaryLabelColor

        NSLayoutConstraint.activate([
            line.centerYAnchor.constraint(equalTo: self.centerYAnchor),
            line.centerXAnchor.constraint(equalTo: self.centerXAnchor),
            line.heightAnchor.constraint(equalToConstant: Pad.separatorHeight),
            line.widthAnchor.constraint(equalTo: self.widthAnchor, multiplier: 0.8 )
        ])
    }
}

然后将其添加到您的视图控制器中：

let separator = Separator()
view.addSubview(separator)
separator.translatesAutoresizingMaskIntoConstraints = false

NSLayoutConstraint.activate([
    separator.trailingAnchor.constraint(equalTo: view.trailingAnchor),
    separator.topAnchor.constraint(equalTo: view.bottomAnchor),
    separator.leadingAnchor.constraint(equalTo: view.leadingAnchor),
    separator.heightAnchor.constraint(equalToConstant: 72.0)
    ])