setNeedsDisplayInRect（quartz2d，iPhone）存在问题

我写了一个函数，每2秒在一个随机位置绘制x个正方形。正方形不能在同一位置绘制两次。应用程序完成一个周期后，将填写表格。现在，当绘制的正方形数时，这很好，我不知道为什么这会起作用；在我看来，您所有的-setNeedsDisplayInRect:调用都将合并到一个更新中。我猜你会喜欢每个方块一个接一个的出现

如果是这种情况，您需要给操作系统时间来循环其事件循环（这些调用只会在当前事件循环之后强制屏幕更新）

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您应该将循环移动到一个单独的方法中，并使用-performSelector:withObject:afterDelay:，或NSTimer调用它。

该死的，就是这么简单。我花了好几个小时调试它，谢谢你的智慧。

- (void)drawRect:(CGRect)rect {
int count = [writeSquares count];

CGContextRef context = UIGraphicsGetCurrentContext();

int radius = 4;

for (int i = 0; i <count; i++)
{
    Square *square = [writeSquares objectAtIndex: i];

    CGContextSetLineWidth(context, 1);
    //CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
    CGContextSetFillColorWithColor(context, [square color].CGColor);
    CGContextMoveToPoint(context, CGRectGetMinX([square squareRect]) + radius, CGRectGetMinY([square squareRect]));
    CGContextAddArc(context, CGRectGetMaxX([square squareRect]) - radius, CGRectGetMinY([square squareRect]) + radius, radius, 3 * M_PI / 2, 0, 0);
    CGContextAddArc(context, CGRectGetMaxX([square squareRect]) - radius, CGRectGetMaxY([square squareRect]) - radius, radius, 0, M_PI / 2, 0);
    CGContextAddArc(context, CGRectGetMinX([square squareRect]) + radius, CGRectGetMaxY([square squareRect]) - radius, radius, M_PI / 2, M_PI, 0);
    CGContextAddArc(context, CGRectGetMinX([square squareRect]) + radius, CGRectGetMinY([square squareRect]) + radius, radius, M_PI, 3 * M_PI / 2, 0);  
    CGContextClosePath(context);
    CGContextFillPath(context);

    //NSLog(@"x = %f x = %f", CGRectGetMaxX([square squareRect]), CGRectGetMinX([square squareRect]));
}

//NSLog(@"Count %i", [writeSquares count]);

[writeSquares removeAllObjects];

-(void)drawInitializer:(int) counter{

if(extra != 0) {
    [self setNeedsDisplay];
    [grid removeAllObjects];
    [self calculateGrid];
    counter = counter + extra;
    clear = YES;
    extra = 0;
}

for(int i=0; i<counter; i++) {
    int count = [grid count];
    NSLog(@"counter %i", count);
    if(count != 144) {
        srandom(time(NULL));
        int r = random() % [coordinates count];

        Coordinate *coordinate = [coordinates objectAtIndex:r];


        Square *square = [Square new];
        [square setSquareRect: CGRectMake ([coordinate x] * 25, [coordinate y] * 25, 20, 20)];
        [square setColor: [UIColor randomColor]];
        [writeSquares addObject:square];
        [grid addObject:square];
        [square release];

        [self setNeedsDisplayInRect:CGRectMake ([coordinate x] * 25, [coordinate y] * 25, 20, 20)];

        [coordinates removeObjectAtIndex:r];
        [coordinate release];
    }
    else {
        extra++;
    }
}

//[newlock release];