在UIView中画线

Question

我需要在UIView中绘制一条水平线。什么是最简单的方法。例如，我想在y-coord = 200处绘制黑色水平线。

我不使用Interface Builder。

Answer 1

在你的情况下（水平线）最简单的方法是添加一个黑色背景颜色和框架[0, 200, 320, 1]的子视图。

代码示例（我希望没有错误 - 我没有Xcode写它）：

UIView *lineView = [[UIView alloc] initWithFrame:CGRectMake(0, 200, self.view.bounds.size.width, 1)];
lineView.backgroundColor = [UIColor blackColor];
[self.view addSubview:lineView];
[lineView release];
// You might also keep a reference to this view 
// if you are about to change its coordinates.
// Just create a member and a property for this...

另一种方法是创建一个将在其drawRect方法中绘制一条线的类（您可以看到我的代码示例为此here）。

Answer 2

也许这有点晚了，但我想补充说有更好的方法。使用UIView很简单，但相对较慢。此方法将覆盖视图如何绘制自身并更快：

- (void)drawRect:(CGRect)rect {
    [super drawRect:rect];

    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);

    // Draw them with a 2.0 stroke width so they are a bit more visible.
    CGContextSetLineWidth(context, 2.0f);

    CGContextMoveToPoint(context, 0.0f, 0.0f); //start at this point

    CGContextAddLineToPoint(context, 20.0f, 20.0f); //draw to this point

    // and now draw the Path!
    CGContextStrokePath(context);
}

Answer 3

Swift 3和Swift 4

这就是你如何在视图的末尾画一条灰线（与b123400的答案相同）

class CustomView: UIView {

    override func draw(_ rect: CGRect) {
        super.draw(rect)

        if let context = UIGraphicsGetCurrentContext() {
            context.setStrokeColor(UIColor.gray.cgColor)
            context.setLineWidth(1)
            context.move(to: CGPoint(x: 0, y: bounds.height))
            context.addLine(to: CGPoint(x: bounds.width, y: bounds.height))
            context.strokePath()
        }
    }
}

Answer 4

只需添加没有文字和背景颜色的标签。设置您选择的坐标以及高度和宽度。您可以手动或使用Interface Builder执行此操作。

Answer 5

您可以为此使用UIBezierPath类：

并且可以根据需要绘制尽可能多的行：

我有UIView的子类：

    @interface MyLineDrawingView()
    {
       NSMutableArray *pathArray;
       NSMutableDictionary *dict_path;
       CGPoint startPoint, endPoint;
    }

       @property (nonatomic,retain)   UIBezierPath *myPath;
    @end

并初始化将用于线条绘制的pathArray和dictPAth对象。我正在编写自己项目代码的主要部分：

- (void)drawRect:(CGRect)rect
{

    for(NSDictionary *_pathDict in pathArray)
    {
        [((UIColor *)[_pathDict valueForKey:@"color"]) setStroke]; // this method will choose the color from the receiver color object (in this case this object is :strokeColor)
        [[_pathDict valueForKey:@"path"] strokeWithBlendMode:kCGBlendModeNormal alpha:1.0];
    }

    [[dict_path objectForKey:@"color"] setStroke]; // this method will choose the color from the receiver color object (in this case this object is :strokeColor)
    [[dict_path objectForKey:@"path"] strokeWithBlendMode:kCGBlendModeNormal alpha:1.0];

}

touchesBegan方法：

UITouch *touch = [touches anyObject];
startPoint = [touch locationInView:self];
myPath=[[UIBezierPath alloc]init];
myPath.lineWidth = currentSliderValue*2;
dict_path = [[NSMutableDictionary alloc] init];

touchesMoved方法：

UITouch *touch = [touches anyObject];
endPoint = [touch locationInView:self];

 [myPath removeAllPoints];
        [dict_path removeAllObjects];// remove prev object in dict (this dict is used for current drawing, All past drawings are managed by pathArry)

    // actual drawing
    [myPath moveToPoint:startPoint];
    [myPath addLineToPoint:endPoint];

    [dict_path setValue:myPath forKey:@"path"];
    [dict_path setValue:strokeColor forKey:@"color"];

    //                NSDictionary *tempDict = [NSDictionary dictionaryWithDictionary:dict_path];
    //                [pathArray addObject:tempDict];
    //                [dict_path removeAllObjects];
    [self setNeedsDisplay];

touchesEnded方法：

        NSDictionary *tempDict = [NSDictionary dictionaryWithDictionary:dict_path];
        [pathArray addObject:tempDict];
        [dict_path removeAllObjects];
        [self setNeedsDisplay];

Answer 6

另一种（甚至更短）的可能性。如果您在drawRect中，请执行以下操作：

[[UIColor blackColor] setFill];
UIRectFill((CGRect){0,200,rect.size.width,1});

Answer 7

根据Guy Daher的回答。

我尽量避免使用？因为如果GetCurrentContext（）返回nil，它可能导致应用程序崩溃。

我会检查是否声明：

class CustomView: UIView 
{    
    override func draw(_ rect: CGRect) 
    {
        super.draw(rect)
        if let context = UIGraphicsGetCurrentContext()
        {
            context.setStrokeColor(UIColor.gray.cgColor)
            context.setLineWidth(1)
            context.move(to: CGPoint(x: 0, y: bounds.height))
            context.addLine(to: CGPoint(x: bounds.width, y: bounds.height))
            context.strokePath()
        }
    }
}

Answer 8

添加没有文字的标签和背景颜色相应的框架尺寸（例如：高度= 1）。通过代码或界面构建器来完成。