如何绘制一个自定义的 UIView，这只是一个圆-iPhone 应用程序

我能不能改变抽屉 方法？

是的:

- (void)drawRect:(CGRect)rect
{
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextAddEllipseInRect(ctx, rect);
CGContextSetFillColor(ctx, CGColorGetComponents([[UIColor blueColor] CGColor]));
CGContextFillPath(ctx);
}

另外，在类本身内更改视图的框架是否可以？

最好不要，但你可以。

或者我需要从不同的类改变帧？

我会让家长来控制。

你可以用石英核来做这个

self.circleView = [[UIView alloc] initWithFrame:CGRectMake(10,20,100,100)];
self.circleView.alpha = 0.5;
self.circleView.layer.cornerRadius = 50;  // half the width/height
self.circleView.backgroundColor = [UIColor blueColor];

下面是使用 UIBezierPath 的另一种方法(也许太晚了 ^ ^) 创建一个圆并用它掩盖 UIView，如下所示:

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 200, 200)];
view.backgroundColor = [UIColor blueColor];


CAShapeLayer *shape = [CAShapeLayer layer];
UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:view.center radius:(view.bounds.size.width / 2) startAngle:0 endAngle:(2 * M_PI) clockwise:YES];
shape.path = path.CGPath;
view.layer.mask = shape;

接近圆形(和其他形状)绘图的另一种方法是使用蒙版。 你画圆圈或其他形状，首先，制作你需要的形状的面具，其次，提供你的颜色的正方形，第三，应用面具的颜色的正方形。您可以更改蒙版或颜色以获得新的自定义圆或其他形状。

#import <QuartzCore/QuartzCore.h>


@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIView *area1;
@property (weak, nonatomic) IBOutlet UIView *area2;
@property (weak, nonatomic) IBOutlet UIView *area3;
@property (weak, nonatomic) IBOutlet UIView *area4;


@end


@implementation ViewController


- (void)viewDidLoad {
[super viewDidLoad];


self.area1.backgroundColor = [UIColor blueColor];
[self useMaskFor: self.area1];


self.area2.backgroundColor = [UIColor orangeColor];
[self useMaskFor: self.area2];


self.area3.backgroundColor = [UIColor colorWithRed: 1.0 green: 0.0 blue: 0.5 alpha:1.0];
[self useMaskFor: self.area3];


self.area4.backgroundColor = [UIColor colorWithRed: 1.0 green: 0.0 blue: 0.5 alpha:0.5];
[self useMaskFor: self.area4];
}


- (void)useMaskFor: (UIView *)colorArea {
CALayer *maskLayer = [CALayer layer];
maskLayer.frame = colorArea.bounds;
UIImage *maskImage = [UIImage imageNamed:@"cirMask.png"];
maskLayer.contents = (__bridge id)maskImage.CGImage;
colorArea.layer.mask = maskLayer;
}


@end

以下是上述代码的输出:

我的贡献:

extension UIView {
func asCircle() {
self.layer.cornerRadius = self.frame.width / 2;
self.layer.masksToBounds = true
}
}

打电话给 myView.asCircle()

斯威夫特3-Xcode 8.1

@IBOutlet weak var myView: UIView!


override func viewDidLoad() {
super.viewDidLoad()


let size:CGFloat = 35.0
myView.bounds = CGRect(x: 0, y: 0, width: size, height: size)
myView.layer.cornerRadius = size / 2
myView.layer.borderWidth = 1
myView.layer.borderColor = UIColor.Gray.cgColor
}

斯威夫特3班:

import UIKit


class CircleView: UIView {


override func draw(_ rect: CGRect) {
guard let context = UIGraphicsGetCurrentContext() else {return}
        

context.addEllipse(in: rect)
context.setFillColor(UIColor.blue.cgColor)
context.fillPath()
}
}