掃描View 效果如下：

擴散View 效果如下：

自定義的程式碼如下：

1. RadarView.h

#import <UIKit/UIKit.h>

typedef NS_ENUM(NSInteger, RadarViewType) {
    RadarViewTypeScan,
    RadarViewTypeDiffuse
};

@interface RadarView : UIView

/** 雷達 空心圓圈的顏色 */
@property (nonatomic, strong) UIColor * radarLineColor;
/** 扇形開始顏色 必須由RGBA值初始化
 *  [UIColor colorWithRed: green: blue: alpha:]
 */
@property (nonatomic, strong) UIColor * startColor;
/** 扇形結束顏色 必須由RGBA值初始化
 *  [UIColor colorWithRed: green: blue: alpha:]
 */
@property (nonatomic, strong) UIColor * endColor;

/**
 *
 *  @param radius       半徑
 *  @param angle        角度
 *  @param radarLineNum 雷達線數量
 *  @param hollowRadius 空心圓半徑
 *
 *  @return 掃描 雷達 View
 */
+ (RadarView *)scanRadarViewWithRadius:(CGFloat)radius
                                 angle:(int)angle
                          radarLineNum:(int)radarLineNum
                          hollowRadius:(CGFloat)hollowRadius;


/**
 *
 *  @param startRadius 擴散圓 起始的半徑
 *  @param endRadius   擴散圓 消失的半徑
 *  @param circleColor 擴散圓 的顏色
 *
 *  @return 擴散 雷達 View
 */
+ (RadarView *)diffuseRadarViewWithStartRadius:(CGFloat)startRadius
                                     endRadius:(CGFloat)endRadius
                                   circleColor:(UIColor *)circleColor;

/**
 *  展示在targerView上
 *
 *  @param targerView <#targerView description#>
 */
- (void)showTargetView:(UIView *)targerView;

- (void)dismiss;

/** 開始掃描動畫 */
- (void)startAnimatian;

/** 停止掃描動畫 */
- (void)stopAnimation;

@end
 

#import "RadarView.h"

#define CenterX self.bounds.size.width*0.5
#define CenterY self.bounds.size.height*0.5

#define DefaultRadarLineColor [UIColor colorWithWhite:1 alpha:0.7]
#define DefaultStartColor [UIColor colorWithRed:1 green:1 blue:1 alpha:0.5]
#define DefaultEndColor [UIColor colorWithRed:1 green:1 blue:1 alpha:0]

#define DefaultCircleColor [UIColor colorWithWhite:1 alpha:0.5]

@interface RadarView ()

#pragma mark - 掃描型別的RadarView 屬性
/** 扇形半徑 */
@property (nonatomic, assign) CGFloat sectorRadius;
/** 扇形 角度 */
@property (nonatomic, assign) int angle;
/** 雷達 空心圓圈的數量 */
@property (nonatomic, assign) int radarLineNum;
/** 中心 空心圓的半徑 (一般 這裡放置一個圓形的頭像) */
@property (nonatomic, assign) int hollowRadius;

#pragma mark - 擴散型別的RadarView 屬性
/** 擴散動畫 起始 的半徑 */
@property (nonatomic, assign) CGFloat startRadius;
/** 擴散動畫 結束 的半徑 */
@property (nonatomic, assign) CGFloat endRadius;
/** 圓圈的顏色 */
@property (nonatomic, strong) UIColor * circleColor;

@property (nonatomic, strong) NSTimer * timer;

@property (nonatomic, assign) RadarViewType radarViewType;

@end

@implementation RadarView

+ (RadarView *)scanRadarViewWithRadius:(CGFloat)radius angle:(int)angle radarLineNum:(int)radarLineNum hollowRadius:(CGFloat)hollowRadius {
    return [[self alloc] initWithRadius:radius angle:angle radarLineNum:radarLineNum hollowRadius:hollowRadius];
}

- (instancetype)initWithRadius:(CGFloat)radius
                         angle:(int)angle
                  radarLineNum:(int)radarLineNum
                  hollowRadius:(CGFloat)hollowRadius {
    if (self = [super init]) {
        self.radarViewType = RadarViewTypeScan;
        self.sectorRadius = radius;
        self.frame = CGRectMake(0, 0, radius*2, radius*2);
        self.angle = angle;
        self.radarLineNum = radarLineNum-1;
        self.hollowRadius = hollowRadius;
        self.backgroundColor = [UIColor clearColor];
    }
    return self;
}

+ (RadarView *)diffuseRadarViewWithStartRadius:(CGFloat)startRadius endRadius:(CGFloat)endRadius circleColor:(UIColor *)circleColor {
    return [[self alloc] initWithStartRadius:startRadius endRadius:endRadius circleColor:circleColor];
}

- (instancetype)initWithStartRadius:(CGFloat)startRadius endRadius:(CGFloat)endRadius circleColor:(UIColor *)circleColor {
    if (self = [super init]) {
        self.radarViewType = RadarViewTypeDiffuse;
        self.frame = CGRectMake(0, 0, endRadius*2, endRadius*2);
        self.startRadius = startRadius;
        self.endRadius = endRadius;
        self.circleColor = circleColor;
        self.backgroundColor = [UIColor clearColor];
    }
    return self;
}

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
    if (_radarViewType == RadarViewTypeScan) {
        if (!_startColor) {
            _startColor = DefaultStartColor;
        }
        if (!_endColor) {
            _endColor = DefaultEndColor;
        }
        if (!_radarLineColor) {
            _radarLineColor = DefaultRadarLineColor;
        }
        
        // 畫雷達線
        [self drawRadarLine];
        
        CGContextRef context = UIGraphicsGetCurrentContext();
        // 把要畫的扇形 分開畫，一次畫1°,每次的顏色漸變
        for (int i = 0; i < _angle; i++) {
            UIColor * color = [self colorWithCurrentAngleProportion:i*1.0/_angle];
            [self drawSectorWithContext:context color:color startAngle:-90-i];
        }
    }
}

/** 畫扇形 */
- (void)drawSectorWithContext:(CGContextRef)context
                        color:(UIColor *)color
                   startAngle:(CGFloat)startAngle {
    //畫扇形，也就畫圓，只不過是設定角度的大小，形成一個扇形
    CGContextSetFillColorWithColor(context, color.CGColor);//填充顏色
    CGContextSetLineWidth(context, 0);//線的寬度
    //以self.radius為半徑圍繞圓心畫指定角度扇形
    CGContextMoveToPoint(context, CenterX, CenterY);
    CGContextAddArc(context, CenterX, CenterY, _sectorRadius, startAngle * M_PI / 180, (startAngle-1) * M_PI / 180, 1);
    CGContextClosePath(context);
    CGContextDrawPath(context, kCGPathFillStroke); //繪製路徑
}


/** 畫雷達線 */
- (void)drawRadarLine {
    CGFloat minRadius = (_sectorRadius-_hollowRadius)*(pow(0.618, _radarLineNum-1));
    /** 畫 圍著空心半徑的第一個空心圓，此圓不在計數內 */
    [self drawLineWithRadius:_hollowRadius+minRadius*0.382];
    
    for (int i = 0; i < _radarLineNum; i++) {
        [self drawLineWithRadius:_hollowRadius + minRadius/pow(0.618, i)];
    }
}

/** 畫空心圓 */
- (void)drawLineWithRadius:(CGFloat)radius {
    CAShapeLayer *solidLine =  [CAShapeLayer layer];
    CGMutablePathRef solidPath =  CGPathCreateMutable();
    solidLine.lineWidth = 1.0f ;
    solidLine.strokeColor = _radarLineColor.CGColor;
    solidLine.fillColor = [UIColor clearColor].CGColor;
    CGPathAddEllipseInRect(solidPath, nil, CGRectMake(self.bounds.size.width*0.5-radius, self.bounds.size.height*0.5-radius, radius*2, radius*2));
    solidLine.path = solidPath;
    CGPathRelease(solidPath);
    [self.layer addSublayer:solidLine];
}

#pragma mark - 展示
- (void)showTargetView:(UIView *)targerView {
    self.center = targerView.center;
    [targerView addSubview:self];
}

#pragma mark - 
- (void)dismiss {
    [self removeFromSuperview];
}

#pragma mark - 開始動畫
- (void)startAnimatian {
    if (_radarViewType == RadarViewTypeScan) {
        CABasicAnimation* rotationAnimation;
        rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
        rotationAnimation.toValue = [NSNumber numberWithFloat: 1 * M_PI * 2.0 ];
        rotationAnimation.duration = 2;
        rotationAnimation.cumulative = YES;
        rotationAnimation.repeatCount = INT_MAX;
        [self.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];
    } else {
        [self diffuseAnimation];
        _timer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(diffuseAnimation) userInfo:nil repeats:YES];
    }
}

#pragma mark - 結束動畫
- (void)stopAnimation {
    if (_radarViewType == RadarViewTypeScan) {
        [self.layer removeAnimationForKey:@"rotationAnimation"];
    } else {
        [_timer invalidate];
        _timer = nil;
    }
}

- (UIColor *)colorWithCurrentAngleProportion:(CGFloat)angleProportion {
    NSArray * startRGBA = [self RGBA_WithColor:_startColor];
    NSArray * endRGBA = [self RGBA_WithColor:_endColor];
    CGFloat currentR = [startRGBA[0] floatValue] - ([startRGBA[0] floatValue]-[endRGBA[0] floatValue]) * angleProportion;
    CGFloat currentG = [startRGBA[1] floatValue] - ([startRGBA[1] floatValue]-[endRGBA[1] floatValue]) * angleProportion;
    CGFloat currentB = [startRGBA[2] floatValue] - ([startRGBA[2] floatValue]-[endRGBA[2] floatValue]) * angleProportion;
    CGFloat currentA = [startRGBA[3] floatValue] - ([startRGBA[3] floatValue]-[endRGBA[3] floatValue]) * angleProportion;
    return [UIColor colorWithRed:currentR green:currentG blue:currentB alpha:currentA];
}

/**
 *  將UIColor物件解析成RGBA 值 的陣列
 *
 *  @param color UIColor物件，有RGBA值 初始化的
 *[UIColor colorWithRed:rValue green:gValue blue:bValue alpha:aValue]
 *
 *  @return 包含RGBA值得陣列[rValue, gValue, bValue, aValue]
 */
- (NSArray *)RGBA_WithColor:(UIColor *)color {
    NSString * colorStr = [NSString stringWithFormat:@"%@", color];
    //將RGB值描述分隔成字串
    NSArray * colorValueArray = [colorStr componentsSeparatedByString:@" "];
    NSString * R = colorValueArray[1];
    NSString * G = colorValueArray[2];
    NSString * B = colorValueArray[3];
    NSString * A = colorValueArray[4];
    return @[R, G, B, A];
}

/** 畫圓 */
- (UIImage *)drawCircle {
    UIGraphicsBeginImageContext(CGSizeMake(_endRadius*2, _endRadius*2));
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextMoveToPoint(context, CenterX, CenterY);
    CGContextSetFillColorWithColor(context, _circleColor.CGColor);
    CGContextAddArc(context, CenterX, CenterY, _endRadius, 0, -2*M_PI, 1);
    CGContextFillPath(context);
    UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return img;
}

- (void)diffuseAnimation {
    UIImageView * imgView = [[UIImageView alloc] init];
    imgView.image = [self drawCircle];
    imgView.frame = CGRectMake(0, 0, _startRadius, _startRadius);
    imgView.center = CGPointMake(CenterX, CenterY);
    [self addSubview:imgView];
    
    [UIView animateWithDuration:2 delay:0 options:UIViewAnimationOptionCurveEaseIn animations:^{
        imgView.frame = CGRectMake(0, 0, _endRadius*2, _endRadius*2);
        imgView.center = CGPointMake(CenterX, CenterY);
        imgView.alpha = 0;
    } completion:^(BOOL finished) {
        [imgView removeFromSuperview];
    }];
}

@end
 

#import "ViewController.h"
#import "RadarView.h"

@interface ViewController ()

@property (nonatomic, strong) RadarView * scanRadarView;
@property (nonatomic, strong) RadarView * diffuseRadarView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    /** 掃描 型別 RadarView */
//    _scanRadarView = [RadarView scanRadarViewWithRadius:self.view.bounds.size.width*0.5 angle:400 radarLineNum:5 hollowRadius:0];
    
    /** 擴散 型別 RadarView */
    _diffuseRadarView = [RadarView diffuseRadarViewWithStartRadius:7 endRadius:self.view.bounds.size.width*0.5 circleColor:[UIColor whiteColor]];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    
//    [_scanRadarView showTargetView:self.view];
//    [_scanRadarView startAnimatian];
    
    [_diffuseRadarView showTargetView:self.view];
    [_diffuseRadarView startAnimatian];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end