IOS(UI)_手勢2(簡單畫板)

簡單畫板

先創建一個UIView 名字AppView

重寫initWithFrame方法：

-(id)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame])
    {
        //UIView的背景顏色
        self.backgroundColor = [UIColor whiteColor];
        //是否可以交互
        self.userInteractionEnabled = YES;
        //是否允許多個手指
        self.multipleTouchEnabled = YES;
        linesArray = [NSMutableArray array];
    }
    return self;
}

然後在本類的drawRect：

    - (void)drawRect:(CGRect)rect {

    //拿到畫板
    CGContextRef context = UIGraphicsGetCurrentContext();

    //設置畫筆粗細和顏色
    CGContextSetLineWidth(context, 5);
    CGContextSetStrokeColorWithColor(context, [UIColor colorWithRed:34/255.0 green:199/255.0 blue:1.0 alpha:1].CGColor);


    for (int i = 0; i < linesArray.count; i++)
    {
        NSArray *pointsArray = linesArray[i];

        //拿到第一個點
        CGContextMoveToPoint(context, [pointsArray[0] CGPointValue].x, [pointsArray[0] CGPointValue].y);

        for (int j = 1; j< pointsArray.count; j++)
        {
            //對剩下座標每個座標進行繪畫
            CGContextAddLineToPoint(context, [pointsArray[j] CGPointValue].x, [pointsArray[j] CGPointValue].y);
        }

    }
    //繪畫
    CGContextStrokePath(context);
}

添加手勢：

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    NSLog(@"手指放在上面");
    //的到手指開始座標
    points = [NSMutableArray array];

    UITouch *touch = touches.anyObject;
    CGPoint point = [touch locationInView:self];
    [pointArray addObject:[NSValue valueWithCGPoint:point]];

    //把開始座標放進數組 pointArray爲全局變量NSMutableArray
    [linesArray addObject:pointArray];
    NSLog(@"%lu",(unsigned long)linesArray.count);
}

-(void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    NSLog(@"手指移動");
    //的到手指座標
    UITouch *touch = touches.anyObject;
    CGPoint point = [touch locationInView:self];
    //大數組嵌套小數組的方法
    [pointArray addObject:[NSValue valueWithCGPoint:point]];

    //調用drawRect方法 重新繪畫
    [self setNeedsDisplay];
}

-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    NSLog(@"手指離開屏幕");

}