【IOS功能实现】简单画线

1.image中画线方法

- (void)viewDidLoad {  
    [super viewDidLoad];  
   
    UIImageView *imageView=[[UIImageView alloc] initWithFrame:self.view.frame];  
    [self.view addSubview:imageView];  
   
    self.view.backgroundColor=[UIColor blueColor];  
   
    UIGraphicsBeginImageContext(imageView.frame.size);  
    [imageView.image drawInRect:CGRectMake(0, 0, imageView.frame.size.width, imageView.frame.size.height)];  
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);  //边缘样式
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 15.0);  //线宽
    CGContextSetAllowsAntialiasing(UIGraphicsGetCurrentContext(), YES);  
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);  //颜色  
    CGContextBeginPath(UIGraphicsGetCurrentContext());  
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), 100, 100);  //起点坐标
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), 200, 100);   //终点坐标
    CGContextStrokePath(UIGraphicsGetCurrentContext());  
    imageView.image=UIGraphicsGetImageFromCurrentImageContext();  
    UIGraphicsEndImageContext();  
}

2.获取当前Context画线方法：（未主动创建path）

CGContextRef ctx = UIGraphicsGetCurrentContext();//获取当前ctx

CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
        CGContextSetLineWidth(ctx, 15.0);  //线宽
        CGContextSetAllowsAntialiasing(ctx, YES);
        CGContextSetRGBStrokeColor(ctx, 1.0, 0.0, 0.0, 1.0);  //颜色
        CGContextBeginPath(ctx);
        CGContextMoveToPoint(ctx, 100, 100);  //起点坐标
        CGContextAddLineToPoint(ctx, 200, 100);   //终点坐标
        CGContextStrokePath(ctx);

其他画线：
    //画两条射线
    // 创建一个Path句柄
    CGMutablePathRef pathRef = CGPathCreateMutable();
    // 初始化该path到一个初始点
    CGPathMoveToPoint(pathRef, &CGAffineTransformIdentity, 100.0f, 0.0f);
    // 添加一条直线，从初始点到该函数指定的坐标点
    CGPathAddLineToPoint(pathRef, &CGAffineTransformIdentity, 150.0f, 100.0f);
    CGPathMoveToPoint(pathRef, &CGAffineTransformIdentity, 100.0f, 0.0f);
    CGPathAddLineToPoint(pathRef, &CGAffineTransformIdentity, 100.0f, 150.0f);
    CGPathCloseSubpath(pathRef);
    // 关闭该path
    CGPathCloseSubpath(pathRef);
    // 将此path添加到Quartz上下文中
    CGContextAddPath(ctx, pathRef);
    // 对上下文进行描边
    CGContextStrokePath(ctx);
    
    //画三角形
    //CGMutablePathRef pathRef = CGPathCreateMutable();
    // 初始化该path到一个初始点
    CGPathMoveToPoint(pathRef, &CGAffineTransformIdentity, 0.0f, 0.0f);
    // 添加一条直线，从初始点到该函数指定的坐标点
    CGPathAddLineToPoint(pathRef, &CGAffineTransformIdentity, 50.0f, 100.0f);
    CGPathAddLineToPoint(pathRef, &CGAffineTransformIdentity, 100.0f, 50.0f);
    // 关闭该path
    CGPathCloseSubpath(pathRef);
    // 关闭该path
    CGPathCloseSubpath(pathRef);
    // 将此path添加到Quartz上下文中
    CGContextAddPath(ctx, pathRef);
    
    // 对上下文进行描边
    CGContextStrokePath(ctx);