iOS绘制专属于程序猿的浪漫爱心

//
// HeartView.h
// DrawHeart
//
// Created by WQL on 16/3/1.
// Copyright © 2016年 WQL. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface HeartView : UIView
/**
 * 比率
 */
@property (nonatomic,assign) CGFloat rate;
/**
 * 填充的颜色
 */
@property (nonatomic,strong) UIColor *fillColor;
/**
 * 线条的颜色
 */
@property (nonatomic,strong) UIColor *strokeColor;
/**
 * 线条的宽度
 */
@property (nonatomic,assign) CGFloat lineWidth;
@end

//
// HeartView.m
// DrawHeart
//
// Created by WQL on 16/3/1.
// Copyright © 2016年 WQL. All rights reserved.
//

#import "HeartView.h"
//间距
NSInteger const spaceWidth = 5;
//波浪的振幅
NSInteger const waveAmplitude = 5;
@interface HeartView ()
{
  CGFloat t;
}
@end

@implementation HeartView

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

- (void)drawRect:(CGRect)rect
{
  [super drawRect:rect];
  
  //上面的两个半圆 半径为整个frame的四分之一
  CGFloat radius = MIN((self.frame.size.width-spaceWidth*2)/4, (self.frame.size.height-spaceWidth*2)/4);
  
  //左侧圆心 位于左侧边距＋半径宽度
  CGPoint leftCenter = CGPointMake(spaceWidth+radius, spaceWidth+radius);
  //右侧圆心 位于左侧圆心的右侧 距离为两倍半径
  CGPoint rightCenter = CGPointMake(spaceWidth+radius*3, spaceWidth+radius);
  
  //左侧半圆
  UIBezierPath *heartLine = [UIBezierPath bezierPathWithArcCenter:leftCenter radius:radius startAngle:M_PI endAngle:0 clockwise:YES];

  //右侧半圆
  [heartLine addArcWithCenter:rightCenter radius:radius startAngle:M_PI endAngle:0 clockwise:YES];
  
  //曲线连接到新的底部顶点 为了弧线的效果，控制点，坐标x为总宽度减spaceWidth，刚好可以相切，平滑过度 y可以根据需要进行调整，y越大，所画出来的线越接近内切圆弧
  [heartLine addQuadCurveToPoint:CGPointMake((self.frame.size.width/2), self.frame.size.height-spaceWidth*2) controlPoint:CGPointMake(self.frame.size.width-spaceWidth, self.frame.size.height*0.6)];
  
  //用曲线 底部的顶点连接到左侧半圆的左起点 为了弧线的效果，控制点，坐标x为spaceWidth，刚好可以相切，平滑过度。y可以根据需要进行调整，y越大，所画出来的线越接近内切圆弧（效果是越胖）
  [heartLine addQuadCurveToPoint:CGPointMake(spaceWidth, spaceWidth+radius) controlPoint:CGPointMake(spaceWidth, self.frame.size.height*0.6)];
  
  //线条处理
  [heartLine setLineCapStyle:kCGLineCapRound];
  //线宽
  [self setHeartLineWidthWithPath:heartLine];
  //线条的颜色
  [self setHeartStrokeColor];
  
  //根据坐标点连线
  [heartLine stroke];
  //clipToBounds 切掉多余的部分
  [heartLine addClip];
  
  
  //初始化波浪的构成
  UIBezierPath *waves = [UIBezierPath bezierPath];
  
  //首先 把起始点设置为左侧 x坐标为spaceWidth 心形从下往上填充,y坐标需要满足一定的函数关系式，当rate为0时，位置为总高度－2倍的留白距离（spaceWidth）＋波浪的振幅；当rate为1时，位置为留白距离（spaceWidth）－振幅。由这两个状态构建函数表达式，即可得到如下表达式
  CGPoint startPoint = CGPointMake(spaceWidth, (self.frame.size.height-3*spaceWidth+waveAmplitude*2)*(1-self.rate)+spaceWidth-waveAmplitude);
  [waves moveToPoint:startPoint];
  
  //关键的地方来了 波浪线怎么画？
  //首先，x坐标是从左往右连续的 y坐标是起始的高度加上一定的波动 这里选择了cos函数。5是波动的幅度大小，50控制的是波峰的间距，t是为了让其动起来，随时间发生波动
  for (int i = 0; i<self.frame.size.width-spaceWidth*2+self.lineWidth*2; i++) {
    //x是要考虑线宽的 不然的话，会导致填充的宽度不够 y就是在某个值附近波动
    CGPoint middlePoint = CGPointMake(spaceWidth+i-self.lineWidth, startPoint.y+waveAmplitude*cos(M_PI/50*i+t));
    
    [waves addLineToPoint:middlePoint];
  }
  
  //画波浪线的右端 到底部的垂直线
  [waves addLineToPoint:CGPointMake(self.frame.size.width-spaceWidth*2, self.frame.size.height-spaceWidth*2)];
  //画右侧底部的点 到达左侧底部的点之间的横线
  [waves addLineToPoint:CGPointMake(spaceWidth, self.frame.size.height-spaceWidth*2)];
  //设置填充颜色
  [self setHeartFillColor];
  //填充
  [waves fill];
  
}
//设置线条宽度 默认为1
- (void)setHeartLineWidthWithPath:(UIBezierPath*)path
{
  CGFloat lineW;
  if (self.lineWidth) {
    lineW = self.lineWidth;
  }else{
    lineW = 1;
  }
  
  [path setLineWidth:lineW];
}

//设置线条颜色
- (void)setHeartStrokeColor
{
  UIColor *strokColor;
  if (self.strokeColor) {
    strokColor = self.strokeColor;
  }else{
    strokColor = [UIColor blackColor];
  }
  
  [strokColor set];
}
//设置填充的颜色
- (void)setHeartFillColor
{
  UIColor *fillColor;
  if (self.fillColor) {
    fillColor = self.fillColor;
  }else{
    fillColor = [UIColor orangeColor];
  }
  
  [fillColor set];

}

//为了实现动态的效果，加一个Timer
- (void)loadTimer
{
  NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.02 target:self selector:@selector(timerAction) userInfo:nil repeats:YES];
  [timer fire];
}
//t 是一个影响波浪线的参数，每次修改之，再画，则每次的都不一样，则有动态的效果
- (void)timerAction
{
  t += M_PI/50;
  
  if (t == M_PI) {
    t = 0;
  }
  //修改了t之后 要调用draw方法
  [self setNeedsDisplay];
}

@end一些关键点，我已经注释啦～

//
// ViewController.m
// DrawHeart
//
// Created by WQL on 16/3/1.
// Copyright © 2016年 WQL. All rights reserved.
//

#import "ViewController.h"
#import "HeartView.h"

NSInteger const heartWidth = 200;
NSInteger const heartHeight = 200;

@interface ViewController ()
{
 HeartView *heartView;
}
@end

@implementation ViewController

- (void)viewDidLoad {
 [super viewDidLoad];
 heartView = [[HeartView alloc]initWithFrame:CGRectMake((self.view.frame.size.width-heartWidth)/2, (self.view.frame.size.height-heartHeight)/2, heartWidth, heartHeight)];

 heartView.rate = 0.5;
 heartView.lineWidth = 1;
 heartView.strokeColor = [UIColor blackColor];
 heartView.fillColor = [UIColor redColor];
 heartView.backgroundColor = [UIColor clearColor];
 [self.view addSubview:heartView];
 
 [self loadSlider];
}

- (void)loadSlider
{
 UISlider *valueSlider = [[UISlider alloc]initWithFrame:CGRectMake((self.view.frame.size.width-300)/2, self.view.frame.size.height-150, 300, 50)];
 valueSlider.minimumValue = 0.0;
 valueSlider.maximumValue = 1.0;
 valueSlider.value = 0.5;
 [valueSlider addTarget:self action:@selector(valueChangedAction:) forControlEvents:UIControlEventValueChanged];
 [self.view addSubview:valueSlider];
}

- (void)valueChangedAction:(UISlider*)slider
{
 heartView.rate = slider.value;
}


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

@end