我需要在UIView中画一条水平线。最简单的方法是什么?例如,我想要在y坐标为200处画一条黑色的水平线。
我不使用Interface Builder。
也许有点晚了,但我想补充一下,有一种更好的方法。 使用UIView很简单,但相对较慢。这种方法覆盖了视图如何绘制自己,并且更快:
- (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);
}
在您的情况下(水平线),最简单的方法是添加一个带有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-我是在没有使用Xcode的情况下编写的):
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类,在其drawRect方法中画一条线(您可以在这里查看我的代码示例)。
以下是如何在视图末尾绘制灰色线条的方法(与 b123400 的答案类似)
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()
}
}
}
只需添加一个没有文字但带有背景颜色的标签。 设置您选择的坐标、高度和宽度。 您可以手动添加,也可以使用界面生成器。
您可以使用UIBezierPath类来实现此功能:
并且可以绘制任意数量的线条:
我已经创建了一个UIView的子类:
@interface MyLineDrawingView()
{
NSMutableArray *pathArray;
NSMutableDictionary *dict_path;
CGPoint startPoint, endPoint;
}
@property (nonatomic,retain) UIBezierPath *myPath;
@end
并初始化了将用于线条绘制的pathArray和dictPAth对象。我正在撰写自己项目的主要代码:
- (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];
}
touchesBegin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];
还有一种可能性(甚至更短)。如果你在drawRect内部,可以尝试以下代码:
[[UIColor blackColor] setFill];
UIRectFill((CGRect){0,200,rect.size.width,1});
这是我能找到的最简单的...
let lineView = UIView(frame: CGRect(x: 4, y: 50, width: self.view.frame.width, height: 1))
lineView.backgroundColor = .lightGray
self.view.addSubview(lineView)
根据Guy Daher的回答。
我尽量避免使用?,因为如果GetCurrentContext()返回nil,它可能会导致应用程序崩溃。
我会使用if语句进行nil检查:
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()
}
}
}
if
语句的原因仅仅是为了从可选类型中取出值,建议使用 guard
语句。 - Julio Flores