objective-c – CGRectMake中Rectangle的原点

for (UITouch *touch in touches) {

    CGPoint touchPoint = [touch locationInView:self.view];

    NSLog(@"touch @ %f,%f",touchPoint.x,touchPoint.y);

    // build a rectangle where we want to capture a URL tap
    CGRect rectangle = CGRectMake(0,480,320,100);

    NSLog(@"midX,midY = %f,CGRectGetMidX(rectangle),CGRectGetMidY(rectangle));

    // check to see if they tapped the URL    
    if (CGRectContainsPoint(rectangle,touchPoint)) {
        NSLog(@"You touched inside the rectangle.");
    }        
}

现在这段代码没有按预期工作……从矩形中点开始的日志显示我的矩形是在midX,midY = 160.000000,530.000000.根据CGPoint文档,原点(0,480)是左下角,但这就像原点是左上角.

当我将矩形的原点更改为0,380时,一切都按预期工作.也许我今天早上没有适当的咖啡因,但为什么我看到文档和执行之间的这种差异？