Question

我按照一个教程创建了一个图表。这是Part 3 tutorial，但是我运行图表时没有显示。这是我的代码：

Gridview.h

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

@interface GridView : UIView

@end



**GridView.m**




    #import "GridView.h"

    @implementation GridView

    - (void)drawLineGraphWithContext:(CGContextRef)ctx
    {
        //float data[] = {0.7, 0.4, 0.9, 1.0, 0.2, 0.85, 0.11, 0.75, 0.53, 0.44, 0.88, 0.77, 0.99, 0.55};
         float data[] = {0.7, 0.4, 0.9, 1.0, 0.2, 0.85, 0.11, 0.75, 0.53, 0.44, 0.88, 0.77, 0.99, 0.55};

        CGContextSetLineWidth(ctx, 2.0);
        CGContextSetStrokeColorWithColor(ctx, [[UIColor colorWithRed:1.0 green:0.5 blue:0 alpha:1.0] CGColor]);

        int maxGraphHeight = kGraphHeight - kOffsetY;
        CGContextBeginPath(ctx);
        CGContextMoveToPoint(ctx, kOffsetX, kGraphHeight - maxGraphHeight * data[0]);

        for (int i = 1; i < sizeof(data); i++)
        {
            CGContextAddLineToPoint(ctx, kOffsetX + i * kStepX, kGraphHeight - maxGraphHeight * data[i]);
        }

        CGContextDrawPath(ctx, kCGPathStroke);

    }




- (void)drawRect:(CGRect)rect



{


    CGContextRef context = UIGraphicsGetCurrentContext();
    [self drawLineGraphWithContext:context];

    // Draw the background image
    UIImage *image = [UIImage imageNamed:@"background.png"];
    CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);
    CGContextDrawImage(context, imageRect, image.CGImage);

    CGContextSetLineWidth(context, 0.6);
    CGContextSetStrokeColorWithColor(context, [[UIColor lightGrayColor] CGColor]);
    CGFloat dash[] = {2.0, 2.0};
    CGContextSetLineDash(context, 0.0, dash, 2);

    // 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);
    }

    int howManyHorizontal = (kGraphBottom - kGraphTop - kOffsetY) / kStepY;
    for (int i = 0; i <= howManyHorizontal; i++)
    {
        CGContextMoveToPoint(context, kOffsetX, kGraphBottom - kOffsetY - i * kStepY);
        CGContextAddLineToPoint(context, kDefaultGraphWidth, kGraphBottom - kOffsetY - i * kStepY);
    }

    CGContextStrokePath(context);
    CGContextSetLineDash(context, 0, NULL, 0); // Remove the dash
}

viewcontroller.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController
{

    UIScrollView *scroller;
}

@property (weak, nonatomic) IBOutlet UIScrollView *scrollView;

@end

viewcontroller.m

#import "ViewController.h"
#import "GridView.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    scroller.contentSize = CGSizeMake(kDefaultGraphWidth, kGraphHeight);

}

为什么我无法生成要显示的图表。请帮我解决。感谢

Answer 1

尝试在view controller.m中添加此方法

-(void)viewDidAppear:(BOOL)animated{

    [super viewDidAppear:animated];

   GridView *gv=[GridView alloc]initWithFrame:CGRectMake(0,0,100,100)];

   [ self.view addSubView:gv];

}

图表未显示在屏幕中

1 个答案: