绘制如图的走势图，原理其实很简单。需要用到CGContext，确定选中的数字，获取选中数字的坐标，然后根据坐标在两个选中的数字中绘制连线。
彩票走势图
首先定义几个宏定义：
#define maxNum 10 // 假设每行都10个数字
#define FormWidth [[UIScreen mainScreen] bounds].size.width/(maxNum+1) // 每个放个都长宽
#define FormHeight FormWidth
#define SCREEN_WIDTH [[UIScreen mainScreen] bounds].size.width
定义几个数组来保存数据：
@interface ChartView()
@property (nonatomic , copy) NSArray *xDatas; // 每行的数字为0～9
@property (nonatomic , copy) NSArray *yDatas; // 每列的数据
@property (nonatomic , strong) NSMutableArray *fillDatas; // 来存放选中号码的数组
@property (nonatomic , strong) NSMutableArray *frameArray; // 用来存放坐标的数组
@end
初始化页面，并在数组中填入一些数据：
- (instancetype)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
_yDatas = @[@"01期",@"02期",@"03期",@"04期",@"05期",@"06期",@"07期",@"08期",@"09期",@"10期"];
_xDatas = @[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9"];
// 选中号码数组
_fillDatas = [NSMutableArray new];
_frameArray = [NSMutableArray new];
self.backgroundColor = [UIColor whiteColor];
// 随机取选中号码
for (NSInteger i = 0; i < _xDatas.count; i++) {
NSString *number = [self randomFormArray:_xDatas];
[_fillDatas addObject:number];
}
}
return self;
}
- (NSString *)randomFormArray:(NSArray *)array {
NSInteger count = array.count;
NSInteger index = arc4random() % count;
return [NSString stringWithFormat:@"%ld" , index];
}
下面是主要的绘制部分，原理很简单基本上都有注释就不多说了：
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
// FormHeight 为格子高度 7是离上边界的距离 不设置 就会出现显示边界的线不好控制
// 根据yData数据绘制横向线
for (int i = 0; i <= _yDatas.count; i++) {
if (i < _yDatas.count) {
NSString *date = _yDatas[i];
// 调用计算字符串宽高方法
CGSize size = [self calculationTextIsze:date andSize:CGSizeMake(FormWidth, FormHeight)];
[date drawInRect:CGRectMake((FormWidth-size.width)/2.0, (FormHeight-size.height)/2.0+FormHeight*i+7, FormWidth, FormHeight) withAttributes:@{NSFontAttributeName : [UIFont systemFontOfSize:12] , NSForegroundColorAttributeName : [UIColor blackColor]}];
}
// 设置画笔颜色
// 描边颜色
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGContextSetLineWidth(context, 1);
// 画笔的起始坐标
// 画笔移动到该点开始画线
CGContextMoveToPoint(context, 0, i * FormHeight + 7);
// 画直线到该点
CGContextAddLineToPoint(context, SCREEN_WIDTH, i * FormHeight + 7);
// 根据坐标绘制路径 kCGPathStroke：只有边框
CGContextDrawPath(context, kCGPathStroke);
}
// 设置彩票号码
for (int j = 0; j <= _yDatas.count; j++) {
if (j < maxNum) {
for (int i = 0; i < maxNum; i++) {
NSString *dateStr = _xDatas[j];
CGSize size = [self calculationTextIsze:dateStr andSize:CGSizeMake(FormWidth, FormHeight)];
[dateStr drawInRect:CGRectMake((FormWidth-size.width)/2.0+j*FormWidth+FormWidth,(FormHeight-size.height)/2.0+i*FormHeight+7, FormWidth, FormHeight) withAttributes:@{NSFontAttributeName : [UIFont systemFontOfSize:12] , NSForegroundColorAttributeName : [UIColor blackColor]}];
}
}
// 绘制纵向边界线
CGContextSetStrokeColorWithColor(context, [UIColor grayColor].CGColor);
CGContextSetLineWidth(context, 1);
CGContextMoveToPoint(context, j * FormWidth , 7);
CGContextAddLineToPoint(context, j * FormWidth, maxNum * FormWidth + 7);
CGContextDrawPath(context, kCGPathStroke);
}
// 画填充圆
for (int i = 0; i < _fillDatas.count; i++) {
CGContextSetStrokeColorWithColor(context, [UIColor grayColor].CGColor);
CGContextSetLineWidth(context, 1);
NSString *number = _fillDatas[i];
for (int x = 0 ; x < _xDatas.count; x++) {
if ([number intValue] == x) {
// 画圆
CGContextAddArc(context, FormWidth*x+FormWidth/2+FormWidth, FormHeight*i+FormHeight/2+7, FormHeight/2, 0, M_PI*2, 1);
// 计算出圆的中心点
CGPoint point = CGPointMake(FormWidth*x+FormWidth/2+FormWidth, FormHeight*i+FormHeight/2+7);
NSString *str = NSStringFromCGPoint(point);
// 保存圆中心的位置，给下面连线
[_frameArray addObject:str];
CGContextSetStrokeColorWithColor(context, [UIColor grayColor].CGColor);
CGContextDrawPath(context, kCGPathStroke);
// 填满整个圆
CGContextAddArc(context, FormWidth*x+FormWidth/2+FormWidth, FormHeight*i+FormHeight/2+7, FormWidth/2, 0, M_PI*2, 1);
// 设置填充颜色
CGContextSetFillColorWithColor(context, [UIColor grayColor].CGColor);
// 根据坐标绘制路径 kCGPathFill：只有填充，不绘制边框
CGContextDrawPath(context, kCGPathFill);
NSString *numberStr = [NSString stringWithFormat:@"%@" , number];
CGSize size = [self calculationTextIsze:numberStr andSize:CGSizeMake(FormWidth, FormWidth)];
// 画内容 被选中的号码
[numberStr drawInRect:CGRectMake((FormWidth-size.width)/2.0+x*FormWidth+FormWidth,(FormHeight-size.height)/2.0+i*FormHeight+7, FormWidth, FormHeight) withAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:12],NSForegroundColorAttributeName:[UIColor redColor]}];
}
}
}
// 绘制连线
for (int i = 0; i < _frameArray.count; i++) {
NSString *pointStr = [_frameArray objectAtIndex:i];
CGPoint point = CGPointFromString(pointStr);
// 设置画笔颜色
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGContextSetLineWidth(context, 2);
if (i == 0) {
// 画笔起始坐标
CGContextMoveToPoint(context, point.x, point.y);
} else {
NSString *str1 = [_frameArray objectAtIndex:i-1];
CGPoint point1 = CGPointFromString(str1);
CGContextMoveToPoint(context, point1.x, point1.y);
CGContextAddLineToPoint(context, point.x, point.y);
}
CGContextDrawPath(context, kCGPathStroke);
}
}
// 根据文字内容计算宽高方法
- (CGSize)calculationTextIsze:(NSString *)text andSize:(CGSize)size {
NSMutableParagraphStyle *paragraphStyle = [NSMutableParagraphStyle new];
paragraphStyle.alignment = NSTextAlignmentLeft;
NSDictionary *attributes = @{NSFontAttributeName: [UIFont systemFontOfSize:12] , NSParagraphStyleAttributeName : paragraphStyle};
CGSize contentSize = [text boundingRectWithSize:CGSizeMake(size.width, MAXFLOAT) options:(NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading) attributes:attributes context:nil].size;
return contentSize;
}
绘制简单的走势图就是这些代码，这里也有demo可以下载:(https://github.com/sunbin117/chartView)
