如何使用控制器内部的IBAction在自定义视图中绘制圆

Question

我拖出一个通用视图，并将其连接到我的circleView.m。然后，我在该视图顶部拖出一个圆形矩形按钮，并将一个IBAction连接到它。截至目前，当视图加载时，圆圈会自动绘制到屏幕上。我想做的是，只有当使用drawRect或其他绘制方法按下按钮时，才能在屏幕上绘制圆圈。这是我的代码：

drawCircleViewController.h

#import <UIKit/UIKit.h>
@interface drawCircleViewController : UIViewController
@end

drawCircleViewController.m

#import "drawCircleViewController.h"
#import "circleView.h"
@interface drawCircleViewController()
@property (nonatomic, weak) IBOutlet circleView *circleV;
@end
@implementation drawCircleViewController
@synthesize circleV = _circleV;

- (IBAction)buttonPressedToDrawCircle:(id)sender {
    // This is action I want to use to draw the circle in my circleView.m 
}
@end

circleView.h

#import <UIKit/UIKit.h>
@interface circleView : UIView
@end

circleView.m

#import "circleView.h"
@implementation circleView
- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

- (void)drawCircleAtPoint:(CGPoint)p
               withRadius:(CGFloat)radius 
                inContext:(CGContextRef)context
{
    UIGraphicsPushContext(context);
    CGContextBeginPath(context);
    CGContextAddArc(context, p.x, p.y, radius, 0, 2*M_PI, YES);
    CGContextStrokePath(context);
    UIGraphicsPopContext();
}
- (void)drawRect:(CGRect)rect
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGPoint midpoint;
    midpoint.x = self.bounds.origin.x + self.bounds.size.width / 2;
    midpoint.y = self.bounds.origin.y + self.bounds.size.height / 2;
#define DEFAULT_SCALE 0.90
    CGFloat size = self.bounds.size.width / 2;
    if (self.bounds.size.height < self.bounds.size.width) size = self.bounds.size.height / 2;
    size *= DEFAULT_SCALE;
    CGContextSetLineWidth(context, 5.0);
    [[UIColor blueColor] setStroke];

    [self drawCircleAtPoint:midpoint withRadius:size inContext:context];
}
@end

Answer 1

有了这些，最简单的方法可能是隐藏圆形视图，并在按下按钮时显示它。

否则，您可以在视图中保留BOOL，以表示按钮是否已被点击，并在drawRect:（并使用setNeedsDisplay触发更改）期间进行检查。