版本记录

版本号	时间
V1.0	2017.08.08

前言

quartz是一个通用的术语，用于描述在iOS和MAC OS X 中整个媒体层用到的多种技术包括图形、动画、音频、适配。Quart 2D 是一组二维绘图和渲染API，Core Graphic会使用到这组API，Quartz Core专指Core Animation用到的动画相关的库、API和类。CoreGraphics 是UIKit下的主要绘图系统，频繁的用于绘制自定义视图。Core Graphics是高度集成于UIView和其他UIKit部分的。Core Graphics数据结构和函数可以通过前缀CG来识别。在app中很多时候绘图等操作我们要利用CoreGraphic框架，它能绘制字符串、图形、渐变色等等，是一个很强大的工具。感兴趣的可以看我另外几篇。
1. CoreGraphic框架解析（一）—— 基本概览
 2. CoreGraphic框架解析（二）—— 基本使用

功能要求

实现波浪线的海浪效果，比如中国联通客户端顶部剩余流量的波浪线。

效果图

功能实现

下面还是直接看代码。

1. JJCoreGraphicWaveVC.m

#import "JJCoreGraphicWaveVC.h"
#import "JJCoreGraphicWaveView.h"
#import "Masonry.h"

@interface JJCoreGraphicWaveVC ()

@end

@implementation JJCoreGraphicWaveVC

#pragma mark - Override Base Function

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor whiteColor];
    
    self.title = @"CoreGraphic实现波浪线";
    
    //加载波浪线视图
    JJCoreGraphicWaveView *waveView = [[JJCoreGraphicWaveView alloc] init];
    [self.view addSubview:waveView];
    
    [waveView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.center.equalTo(self.view);
        make.width.equalTo(@300);
        make.height.equalTo(@200);
    }];
}

@end

2. JJCoreGraphicWaveView.m

#import "JJCoreGraphicWaveView.h"

#define kJJCoreGraphicWaveViewScreenWidth       [UIScreen mainScreen].bounds.size.width
#define kJJCoreGraphicWaveViewScreenHeight      [UIScreen mainScreen].bounds.size.height

@interface JJCoreGraphicWaveView ()

@property (nonatomic, strong) UIColor *waterColor;
@property (nonatomic, assign) CGFloat waterLineY;
@property (nonatomic, assign) CGFloat waveAmplitude;
@property (nonatomic, assign) CGFloat waveCycle;
@property (nonatomic, assign) BOOL isIncrease;
@property (nonatomic, strong) CADisplayLink *waveDisplayLink;

@end

@implementation JJCoreGraphicWaveView

#pragma mark - Override Base Function

- (instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {
        [self setInitConfig];
    }
    return self;
}

- (void)drawRect:(CGRect)rect
{
    //初始化画布
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    //推入
    CGContextSaveGState(context);
    
    //定义前波浪path
    CGMutablePathRef frontPath = CGPathCreateMutable();
    
    //定义后波浪path
    CGMutablePathRef backPath = CGPathCreateMutable();
    
    //定义前波浪反色path
    CGMutablePathRef frontReversePath = CGPathCreateMutable();
    
    //定义后波浪反色path
    CGMutablePathRef backReversePath = CGPathCreateMutable();
    
    //画水
    CGContextSetLineWidth(context, 1);
    
    //前波浪位置初始化
    float frontY = self.waterLineY;
    CGPathMoveToPoint(frontPath, NULL, 0, frontY);
    
    //前波浪反色位置初始化
    float frontReverseY = self.waterLineY;
    CGPathMoveToPoint(frontReversePath, NULL, 0,frontReverseY);
    
    //后波浪位置初始化
    float backY = self.waterLineY;
    CGPathMoveToPoint(backPath, NULL, 0, backY);
    
    //后波浪反色位置初始化
    float backReverseY = self.waterLineY;
    CGPathMoveToPoint(backReversePath, NULL, 0, backReverseY);
    
    for(float x = 0; x <= kJJCoreGraphicWaveViewScreenWidth; x ++){
        
        //前波浪绘制
        frontY= _waveAmplitude * sin( x/180 * M_PI + 4 * self.waveCycle/M_PI ) * 5 + self.waterLineY;
        CGPathAddLineToPoint(frontPath, nil, x, frontY);
        
        //后波浪绘制
        backY= _waveAmplitude * cos( x/180 * M_PI + 3 * self.waveCycle/M_PI ) * 5 + self.waterLineY;
        CGPathAddLineToPoint(backPath, nil, x, backY);
        
        if (x>=100) {
            
            //后波浪反色绘制
            backReverseY= _waveAmplitude * cos( x/180 * M_PI + 3 * self.waveCycle/M_PI ) * 5 + self.waterLineY;
            CGPathAddLineToPoint(backReversePath, nil, x, backReverseY);
            
            //前波浪反色绘制
            frontReverseY= _waveAmplitude * sin( x/180 * M_PI + 4 * self.waveCycle/M_PI ) * 5 + self.waterLineY;
            CGPathAddLineToPoint(frontReversePath, nil, x, frontReverseY);
        }
    }
    
    //后波浪绘制
    CGContextSetFillColorWithColor(context, [UIColor greenColor].CGColor);
    CGPathAddLineToPoint(backPath, nil, kJJCoreGraphicWaveViewScreenWidth, rect.size.height);
    CGPathAddLineToPoint(backPath, nil, 0, rect.size.height);
    CGPathAddLineToPoint(backPath, nil, 0, self.waterLineY);
    CGPathCloseSubpath(backPath);
    CGContextAddPath(context, backPath);
    CGContextFillPath(context);
    
    //推入
    CGContextSaveGState(context);
    
    //后波浪反色绘制
    CGPathAddLineToPoint(backReversePath, nil, kJJCoreGraphicWaveViewScreenWidth, rect.size.height);
    CGPathAddLineToPoint(backReversePath, nil, 100, rect.size.height);
    CGPathAddLineToPoint(backReversePath, nil, 100, self.waterLineY);
    
    CGContextAddPath(context, backReversePath);
    CGContextClip(context);

    //弹出
    CGContextRestoreGState(context);
    
    //前波浪绘制
    CGContextSetFillColorWithColor(context, [_waterColor CGColor]);
    CGPathAddLineToPoint(frontPath, nil, kJJCoreGraphicWaveViewScreenWidth, rect.size.height);
    CGPathAddLineToPoint(frontPath, nil, 0, rect.size.height);
    CGPathAddLineToPoint(frontPath, nil, 0, self.waterLineY);
    CGPathCloseSubpath(frontPath);
    CGContextAddPath(context, frontPath);
    CGContextFillPath(context);
    
    //推入
    CGContextSaveGState(context);
    
    //前波浪反色绘制
    CGPathAddLineToPoint(frontReversePath, nil, kJJCoreGraphicWaveViewScreenWidth, rect.size.height);
    CGPathAddLineToPoint(frontReversePath, nil, 100, rect.size.height);
    CGPathAddLineToPoint(frontReversePath, nil, 100, self.waterLineY);
    
    CGContextAddPath(context, frontReversePath);
    CGContextClip(context);
    
    //推入
    CGContextSaveGState(context);
    
    //释放
    CGPathRelease(backPath);
    CGPathRelease(backReversePath);
    CGPathRelease(frontPath);
    CGPathRelease(frontReversePath);
}

#pragma mark - Object Private Function

- (void)setInitConfig
{
    self.backgroundColor = [UIColor clearColor];
    self.waveAmplitude = 3.0;
    self.waveCycle = 1.0;
    self.waterColor = [UIColor colorWithRed:90/255.0 green:200/255.0 blue:140/255.0 alpha:1.0];
    self.waterLineY = 20.0;
    self.waveDisplayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(waveDidRun)];
    [self.waveDisplayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
}

#pragma mark - Action && Notification

//CADisplayLink，每秒60次刷新界面

- (void)waveDidRun
{
    if (self.isIncrease) {
        self.waveAmplitude += 0.03;
    }
    else {
        self.waveAmplitude -= 0.03;
    }
    
    if (self.waveAmplitude <= 1) {
        self.isIncrease = YES;
    }
    
    if (self.waveAmplitude >= 1.5) {
        self.isIncrease = NO;
    }
    
    //速度控制
    self.waveCycle += 0.02;
    
    //调用drawRect方法不停的绘制
    [self setNeedsDisplay];
}

@end

还有几点要说明下：