（void）drawRect：（CGRect）rect iOS 5.1 OpenGL ES 2.0中的错误

Question

我正在尝试通过opengl es 2.0模板在屏幕上绘制图像。 它在MyGLKView的（void）drawRect：（CGRect）rect中显示以下错误。 有什么解决办法吗？ 谢谢！！

CGContextSaveGState：无效上下文0x0
CGContextSetBlendMode：无效的上下文0x0
CGContextSetAlpha：无效的上下文0x0
CGContextTranslateCTM：无效上下文0x0
CGContextScaleCTM：无效上下文0x0
CGContextDrawImage：无效上下文0x0
CGContextRestoreGState：无效的上下文0x0

MyGLKView.m

#import "MyGLKView.h"
@implementation MyGLKView

@synthesize pUIImage;

//- (id)initWithFrame:(CGRect)frame
- (id)initWithFrame:(CGRect)frame context:(EAGLContext *)context
{
    //if (self = [super initWithFrame:frame])
    if (self = [super initWithFrame:frame context:context])
    {
        // Initialization code
        pUIImage = [UIImage imageNamed:@"star-green.png"];
    }
    return self;
}


// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
    [pUIImage drawAtPoint:CGPointMake(0, 0)];
}

@end

ViewController.m

#import "ViewController.h"
#import "MyGLKView.h"

@implementation ViewController

@synthesize pContext;

- (void)viewDidLoad
{
    [super viewDidLoad];
    pContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];

    if (!pContext)
    {
        NSLog(@"Failed to create ES context");
    }

    //MyGLKView *pMyGLKView = [[MyGLKView alloc] init];
    //pMyGLKView.context = pContext;
    //self.view = pMyGLKView;
    self.view = [[MyGLKView alloc] initWithFrame:[[UIScreen mainScreen] bounds] context:pContext];
}

- (void)viewDidUnload
{    
    [super viewDidUnload];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Release any cached data, images, etc. that aren't in use.
}

- (void)update
{

}

@end

Answer 1

GLKView的指定初始值GLKView是GLKView -initWithFrame:context: GLKView 您应该实现而不是-initWithFrame:并在super上调用它。