Chapter 5 帶顏色的同心圓

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一、重寫 DrwaRect

-(void)drawRect:(CGRect)rect{    CGRect bounds = self.bounds;        CGPoint center;    center.x = bounds.origin.x + bounds.size.width / 2.0;    center.y = bounds.origin.y + bounds.size.height / 2.0;        float maxRadius = MAX(bounds.size.width, bounds.size.height);    
　　// 畫圓    UIBezierPath *path = [[UIBezierPath alloc] init];    for(float currentRadius = maxRadius; currentRadius > 0; currentRadius -= 20)    {        [path moveToPoint:CGPointMake(center.x + currentRadius, center.y)];        [path addArcWithCenter:center                        radius:currentRadius                    startAngle:0.0                      endAngle:M_PI * 2.0                     clockwise:YES];    }    path.lineWidth = 10;        // Configure the drawing color of light gray    [self.circleColor setStroke];    [path stroke];        /*    CGContextRef currentContext = UIGraphicsGetCurrentContext();    CGContextSaveGState(currentContext);    [path addClip];        // Gradient triangle    CGFloat location[2] = {0.0, 1.0};    CGFloat components[8] = {1.0, 0.0, 0.0, 1.0, 1.0, 1.0, 0.0, 1.0};    CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();    CGGradientRef gradient = CGGradientCreateWithColorComponents(colorspace, components, location, 2);    CGPoint startPoint = CGPointMake(rect.size.width / 2.0, rect.size.height / 4.0);    CGPoint endPoint = CGPointMake(rect.size.width / 2.0 , rect.size.height * 0.75);    CGContextDrawLinearGradient(currentContext, gradient, startPoint, endPoint, 0);    CGColorSpaceRelease(colorspace);    CGGradientRelease(gradient);            // Add shadow of image    CGContextSetShadow(currentContext, CGSizeMake(4.0, 7.0), 3);    // Draw stuff here, it will appear with a shadow        // Add logo image    UIImage *logoImage = [UIImage imageNamed:@"logo.png"];    CGRect logoRect = CGRectMake(rect.size.width / 4.0, rect.size.height / 4.0, rect.size.width/2.0, rect.size.height / 2.0);    [logoImage drawInRect:logoRect];        CGContextRestoreGState(currentContext);    // Draw stuff here, it will apear with no shadow;        CGContextRelease(currentContext);     */}

二、重寫 touchesBegin:withEvent 

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{//    NSLog(@"%@ was touched", self);        // Get 3 random numbers between 0 and 1    float red = (arc4random() % 100) / 100.0;    float blue = (arc4random() % 100) / 100.0;    float green = (arc4random() % 100) / 100.0;        UIColor *randomColor = [UIColor colorWithRed:red green:green blue:blue alpha:1.0];    self.circleColor = randomColor;}

三、重繪 View

[self setNeedsDisplay];

 

Chapter 5 帶顏色的同心圓