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This article introduces the relevant knowledge of "the methods and steps of iOS to achieve radar scanning effect". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

# import @ interface LTIndicatiorView: UIView@property (nonatomic,strong) UIColor * color;@property (nonatomic,assign) float repeatCount;@property (nonatomic,strong) UIColor * borderColor;@property (nonatomic,assign) float borderWidth;@end @ interface LTRadarView: UIView@property (nonatomic,strong) UIColor * color;@property (nonatomic,strong) UIColor * borderColor;@property (nonatomic,assign) float borderWidth;@property (nonatomic,assign) int pulsingCount;@property (nonatomic,assign) float duration;@property (nonatomic,assign) float repeatCount;@property (nonatomic,strong) CALayer * pulsingLayer @ end

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/ LTRadarView.m// raderScan//// Created by mac on 17 ©2 mac 5. Accord / Copyright Copyright 2017 mac. All rights reserved.// # import "LTRadarView.h" # define Angel 15 @ interface LTRadarButton: UIButton @ end @ implementation LTRadarButton-(void) removeFromSuperview {[UIView beginAnimations:@ "" context:nil]; [UIView setAnimationDuration:0.5]; self.transform = CGAffineTransformMakeScale (0.2,0.2); self.alpha = 0; [UIView setAnimationDidStopSelector:@selector (callSuperRemoveFromSuperview)]; [UIView commitAnimations];}-(void) callSuperRemoveFromSuperview {[super removeFromSuperview] }-(id) initWithFrame: (CGRect) frame {self = [super initWithFrame:frame]; self.alpha = 0; return self;}-(void) didMoveToWindow {[super didMoveToWindow]; self.transform = CGAffineTransformMakeScale (0.2,0.2); if (self.window) {[UIView animateWithDuration:0.5 animations: ^ {self.transform = CGAffineTransformIdentity; self.alpha = 1;}] } @ end @ implementation LTIndicatiorView-(id) initWithFrame: (CGRect) frame {if (self = [super initWithFrame:frame]) {_ color = [UIColor greenColor]; _ repeatCount = HUGE_VALF; _ borderColor = [UIColor redColor]; _ borderWidth = 1.0f;} return self;} / / Only override drawRect: if you perform custom drawing. / / An empty implementation adversely affects performance during animation. -(void) drawRect: (CGRect) rect {/ / Drawing code self.backgroundColor = [UIColor whiteColor]; [super drawRect:rect]; self.layer.cornerRadius = self.frame.size.height/2.0f; self.clipsToBounds = YES; self.layer.borderColor = [UIColor clearColor] .CGColor; self.layer.borderWidth = 50; self.layer.masksToBounds = YES; CGContextRef context = UIGraphicsGetCurrentContext (); for (int I = 0; I

< Angel; i++) { CGFloat alpha = (float)i /(float)600; CGColorRef shadowColor = [[UIColor greenColor] colorWithAlphaComponent:alpha].CGColor;//计算扇形填充颜色 CGContextSetFillColorWithColor(context, shadowColor); CGContextMoveToPoint(context, self.center.x, self.center.y);//指定员心 CGFloat startAngle = (-Angel+i+1.15)/Angel*(float)M_PI; CGFloat endAngle = (-Angel+i-1.15)/Angel*(float)M_PI;// NSLog(@"startAngle = %f endAngle = %f ,alpha = %f",startAngle,endAngle,alpha); CGContextAddArc(context, self.center.x, self.center.y, self.frame.size.height/2.0f,0, 25, 1);//画一个扇形 CGContextClosePath(context); CGContextDrawPath(context, kCGPathFill);//绘制扇形 } CGContextSetLineWidth(context, 1);//扫描线宽度 CGContextSetStrokeColorWithColor(context, [_color colorWithAlphaComponent:1].CGColor);//扫描线颜色 CGContextMoveToPoint(context, self.center.x, self.center.y); CGContextAddLineToPoint(context, self.frame.size.height, self.center.y); CGContextStrokePath(context); CGContextSetRGBStrokeColor(context,255/255.0, 255/255.0, 255/255.0, 0.1);//最外面圆颜色 CGContextSetLineWidth(context, 10);//线宽度 CGContextAddArc(context, self.center.x, self.center.y, self.frame.size.height/2.0, 0, 2*M_PI, 1);//添加一个圆 CGContextDrawPath(context, kCGPathStroke);//绘制路径 CGContextStrokePath(context);//显示绘制 //扫描动画 CABasicAnimation *rotateAnimation = [CABasicAnimation animation]; rotateAnimation.keyPath = @"transform.rotation.z"; rotateAnimation.toValue = @(2*M_PI); rotateAnimation.duration = 3; rotateAnimation.removedOnCompletion = NO; rotateAnimation.repeatCount = _repeatCount; [self.layer addAnimation:rotateAnimation forKey:@"rotate_layer"]; } @end @implementation LTRadarView{ NSMutableArray *items;} - (id)initWithFrame:(CGRect)frame{ if (self = [super initWithFrame:frame]) { items = [NSMutableArray array]; _color = [UIColor redColor]; _borderColor = [UIColor greenColor]; _pulsingCount = 3; _duration = 3; _repeatCount = HUGE_VALF; _borderWidth = 3.0f; } return self;} // Only override drawRect: if you perform custom drawing.// An empty implementation adversely affects performance during animation.- (void)drawRect:(CGRect)rect { // Drawing code [super drawRect:rect]; self.layer.cornerRadius = self.frame.size.height/2; self.clipsToBounds = YES; self.layer.borderColor = [UIColor clearColor].CGColor; self.layer.borderColor = [UIColor clearColor].CGColor; self.layer.borderWidth = 50; self.layer.masksToBounds = YES; CGContextRef ctx = UIGraphicsGetCurrentContext(); CGContextSetRGBFillColor(ctx, 0/255.0, 0/255.0, 0/255.0, 1);//圆颜色 CGContextSetLineWidth(ctx, 1);//宽度 CGContextAddArc(ctx, self.center.x, self.center.y, self.frame.size.height/2, 0, 2*M_PI, 1);//添加一个圆 CGContextDrawPath(ctx, kCGPathStroke);//绘制 CGContextStrokePath(ctx);//显示 CALayer *animationLayer = [CALayer layer]; animationLayer.frame = self.layer.frame; for (int i = 0; i < _pulsingCount; i++) { CALayer *pulsingLayer = [CALayer layer]; pulsingLayer.frame = CGRectMake(0, 0, rect.size.width, rect.size.height); pulsingLayer.borderColor = [UIColor clearColor].CGColor; pulsingLayer.borderWidth = 1; pulsingLayer.cornerRadius = rect.size.height/2; pulsingLayer.backgroundColor = [UIColor redColor].CGColor; CAAnimationGroup *animationGroup = [CAAnimationGroup animation]; animationGroup.fillMode = kCAFillModeBoth; animationGroup.beginTime = CACurrentMediaTime() + (float) i * _duration / _pulsingCount; animationGroup.duration = _duration; animationGroup.repeatCount = HUGE_VALF; animationGroup.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]; animationGroup.autoreverses = NO; animationGroup.delegate = self; animationGroup.removedOnCompletion = NO; CABasicAnimation *scaleAnimation = [CABasicAnimation animation]; scaleAnimation.keyPath = @"transform.scale"; scaleAnimation.removedOnCompletion = NO; scaleAnimation.fromValue = @(0.0f); scaleAnimation.toValue = @1.0f; scaleAnimation.autoreverses = NO; CAKeyframeAnimation *opacityAnimation = [CAKeyframeAnimation animation]; opacityAnimation.keyPath = @"opacity"; opacityAnimation.values = @[@1.0,@0.75,@0.5,@0.25,@0.0]; opacityAnimation.keyTimes = @[@0.0,@0.25,@0.5,@0.75,@1]; opacityAnimation.autoreverses = NO; opacityAnimation.removedOnCompletion = NO; animationGroup.animations = @[scaleAnimation,opacityAnimation]; [pulsingLayer addAnimation:animationGroup forKey:@"pulsing"]; [animationLayer addSublayer:pulsingLayer]; } [self.layer addSublayer:animationLayer]; [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(addOrReplaceItem) userInfo:nil repeats:YES];} - (void)animation:(CALayer *)layer{ CAAnimationGroup *animationGroup = [CAAnimationGroup animation]; animationGroup.fillMode = kCAFillModeBoth; animationGroup.beginTime = CACurrentMediaTime() + 1 * _duration / _pulsingCount; animationGroup.duration = _duration; animationGroup.repeatCount = HUGE_VALF; animationGroup.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]; animationGroup.autoreverses = NO; animationGroup.delegate = self; animationGroup.removedOnCompletion = NO; CABasicAnimation *scaleAnimation = [CABasicAnimation animation]; scaleAnimation.keyPath = @"transform.scale"; scaleAnimation.removedOnCompletion = NO; scaleAnimation.fromValue = @(0.0f); scaleAnimation.toValue = @1.0f; scaleAnimation.autoreverses = NO; CAKeyframeAnimation *opacityAnimation = [CAKeyframeAnimation animation]; opacityAnimation.keyPath = @"opacity"; opacityAnimation.values = @[@1.0,@0.75,@0.5,@0.25,@0.0]; opacityAnimation.keyTimes = @[@0.0,@0.25,@0.5,@0.75,@1]; opacityAnimation.autoreverses = NO; opacityAnimation.removedOnCompletion = NO; animationGroup.animations = @[scaleAnimation,opacityAnimation]; [layer addAnimation:animationGroup forKey:@"pulsing"]; } #define RandomColor [UIColor colorWithRed:arc4random_uniform(256)/255.0 green:arc4random_uniform(256)/255.0 blue:arc4random_uniform(256)/255.0 alpha:1.0]/* 生成一个在圆里面的坐标 生成的坐标要围绕中心的绿点（圆心），让我们重新翻开数学课本，看看高中数学对三角函数的定义： 在一个平面直角坐标系中，以原点为圆心，1 为半径画一个圆，这个圆交 x 轴于 A 点。以 O 为旋转中心，将 A 点逆时针旋转一定的角度α至 B 点，设此时 B 点的坐标是(x,y)，那么此时 y 的值就叫做α的正弦，记作 sinα；此时 x 的值就叫做α的余弦，记作 cosα；y 与 x 的比值 y/x 就叫做α的正切，记作 tanα。 任意角三角函数 正弦sinθ=y/r, 余弦cosθ=x/r,正切tanθ=y/x,余切cotθ=x/y,正割secθ=r/x,余割cscθ=r/y 锐角三角函数 正弦sinA=a/c, 余弦cosA=b/c,正切tanA=a/b,余切cotA=b/a,正割secA=c/b,余割cscA=c/a 还有一个很重要的公式：圆的参数方程：以点O（a，b）为圆心，以r为半径的圆的参数方程是 x=a+r*cosθ, y=b+r*sinθ, （其中θ为参数） 到这里为止，思路就清晰了，以下是generateCenterPointInRadar的方法实现： */ - (CGPoint)generateCenterPointInRadar{ float angle = arc4random() % 360;//随机一个角度 float radius = arc4random() % (int)((self.bounds.size.width - 44)/2);//随机一个半径， 这里减去44是因为要把这个view显示在圆里面，如果不减44，则有可能会显示在圓外面 double x = cos(angle) * radius;//计算随机出现的一个角度的x坐标 x=a+r*cosθ r = radius, θ = angle ,a ＝ 圆心的x坐标 double y = sin(angle) * radius;//计算随机出现的一个角度的y坐标 y=b+r*sinθ r = radius, θ = angle ,b ＝ 圆心的y坐标 return CGPointMake(x + self.bounds.size.width / 2, y + self.bounds.size.height / 2);//x y 分别加个圆心的坐标即self.center.x.y} - (void)addOrReplaceItem{ int maxCount = 10; LTRadarButton *radarButton = [LTRadarButton buttonWithType:UIButtonTypeCustom]; radarButton.frame = CGRectMake(0, 0, 44, 44); radarButton.backgroundColor = RandomColor; radarButton.layer.cornerRadius = 44/2; do { CGPoint center = [self generateCenterPointInRadar]; radarButton.center = CGPointMake(center.x, center.y); } while ([self itemFrameIntersectsInOtherItem:radarButton.frame]); [self addSubview:radarButton]; [items addObject:radarButton]; if (items.count >

MaxCount) {UIView * view = [items firstObject]; [view removeFromSuperview]; [items removeObject:view] }} / * when we generate the center of each item, we do not compare it with the existing item, which is a performance-consuming operation. If your itemSize is too large and maxCount is too much, it can even lead to an endless loop. In that case, you may limit the number of loops as well as the itemSize and maxCount. If you generate an item center, you may have too many loops. It can be seen as entering an endless loop, in which case you can only recalculate the existing centers. This extreme situation is not considered here, because with the current cooperation of itemSize and maxCount, there will be no endless cycle. We add an itemFrameIntersectsInOtherItem private method to determine whether it overlaps with the previously generated center: * /-(BOOL) itemFrameIntersectsInOtherItem: (CGRect) frame {for (UIView * item in items) {if (CGRectIntersectsRect (item.frame, frame)) {return YES;}} return NO } this is the end of the content of "methods and steps for iOS to achieve radar scanning effect". Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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