Question

so I am trying to draw some grid lines that in landscape go all the way down to the bottom, however when I switch to landscape the the graph doesn’t follow and the grid lines go smaller.

I have set the

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return YES;
}

However it still doesn’t work, here is my code. Can anyone spot the problem? this is the custom view file, the view controller is the default apart from the code above that returns yes.

.h file

#import <UIKit/UIKit.h>
#define kGraphHeight 300
#define kDefaultGraphWidth 900
#define kOffsetX 10
#define kStepX 50
#define kGraphBottom 300
#define kGraphTop 0

@interface GraphView : UIView

@end

And here is the implementation

- (void)drawRect:(CGRect)rect
{
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetLineWidth(context, 0.6);
    CGContextSetStrokeColorWithColor(context, [[UIColor lightGrayColor] CGColor]);

    // How many lines?
    int howMany = (kDefaultGraphWidth - kOffsetX) / kStepX;
    // Here the lines go
    for (int i = 0; i < howMany; i++)
    {
        CGContextMoveToPoint(context, kOffsetX + i * kStepX, kGraphTop);
        CGContextAddLineToPoint(context, kOffsetX + i * kStepX, kGraphBottom);
    }

    CGContextStrokePath(context);

}

Any help would be appreciated

btw I am following this tutorial

http://buildmobile.com/creating-a-graph-with-quartz-2d/#fbid=YDPLqDHZ_9X

Answer 1

You need to do three things:

1. In Interface Builder, select the view containing the graph and drag it so it fills the screen.
2. In Interface Builder, set the Autosizing masks on the view so it continues to fill the screen after rotation. You can change the simulated metrics of the outer view to make sure this happens.
3. The kGraphTop and kGraphBottom constants mean it only draws from 0 to 300 pixels. You could just make kGraphBottom larger, but that would not be reliable. Instead, you want to find the size of the view bounds and fill them from top to bottom.

Here’s how to fill the bounds:

- (void) drawRect:(CGRect)rect
{
    // Get the size of the view being drawn to.
    CGRect bounds = [self bounds];

    CGContextSetLineWidth(context, 0.6);
    CGContextSetStrokeColorWithColor(context, [[UIColor lightGrayColor] CGColor]);

    // How many lines?
    int howMany = (bounds.size.width - kOffsetX) / kStepX;
    // Here the lines go
    for (int i = 0; i < howMany; i++)
    {
        // Start at the very top of the bounds.
        CGContextMoveToPoint(context, bounds.origin.x+kOffsetX + i * kStepX, bounds.origin.y);
        // Draw to the bottom of the bounds.
        CGContextAddLineToPoint(context, bounds.origin.x+kOffsetX + i * kStepX, bounds.origin.y+bounds.size.height);
    }

    CGContextStrokePath(context);
}