iOS使用对象上下文创建简易画板

之前有写过一篇iOS使用贝塞尔曲线创建简易画板，可以跟这篇做一个对比。

依然是先看效果：

原理跟iOS使用贝塞尔曲线创建简易画板中介绍的基本相同，不做详细说明了，直接上主要代码：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    UITouch *touch = [touches anyObject];
    
    CGPoint beginPoint = [touch locationInView:touch.view];
    
    NSMutableArray *subarray = [NSMutableArray array];
    [subarray addObject:[NSValue valueWithCGPoint:beginPoint]];
    [self.totalPathPoints addObject:subarray];
}


- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    [self drawLineWithTouches:touches];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    [self drawLineWithTouches:touches];
}


- (void)drawLineWithTouches:(NSSet *)touches {

    UITouch *touch = [touches anyObject];
    
    CGPoint movePoint = [touch locationInView:touch.view];
    
    
    NSMutableArray *subarray = [self.totalPathPoints lastObject];
    
    [subarray addObject:[NSValue valueWithCGPoint:movePoint]];
    
    [self setNeedsDisplay];

}

在drawRect方法当中：

  CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    
    for (NSMutableArray *arr in self.totalPathPoints) {
        for (int i = 0; i < arr.count; i++) {
            
            if (i == 0) {
                CGPoint startPoint = [arr[i] CGPointValue];
                CGContextMoveToPoint(ctx, startPoint.x, startPoint.y);
                
            }
            else{
                CGPoint movePoint = [arr[i] CGPointValue];
                CGContextAddLineToPoint(ctx, movePoint.x, movePoint.y);
            }
        }
        
    }
    
    CGContextSetLineJoin(ctx, kCGLineJoinRound);
    CGContextSetLineCap(ctx, kCGLineCapRound);
    CGContextSetLineWidth(ctx, 5);
    
    CGContextStrokePath(ctx);

这里放上demo