사용자의 CALayer - 유효하지 않은 컨텍스트 0x0으로

Question

내가 레이어를 사용하는 응용 프로그램을 구축하기 위해 노력하고있어

는 내 응용 프로그램 구조는 내가 LayersView에 여러 레이어를 추가 할

UIView --> UIScrollView --> UIView --> LayersView (Custom UIView) 
            --> UIImageView 

, 그래서 정의를 구축했습니다 CALayerUIBezierPath을 사용하여 점 집합을 그립니다.

CALayerBezierPath.h

#import <QuartzCore/QuartzCore.h> 

@interface CALayerBezierPath : CALayer { 
    NSMutableArray *pointsArray; 
} 
@property (nonatomic, retain) NSMutableArray *pointsArray; 

- (void) initVariables; 
- (void) addNewPoints:(CGPoint)newPoint; 
@end 

CALayerBezierPath.m

내 LayrsView에서 새 레이어를 시작하고있어

#import "CALayerBezierPath.h" 

@implementation CALayerBezierPath 

@dynamic pointsArray; 

-(void)drawInContext:(CGContextRef)ctx { 
    NSLog(@"CALayerBezierPath - drawInContext"); 
    if ([pointsArray count] > 0) { 
     UIColor *color = [UIColor redColor]; 
     [color set]; 
     UIBezierPath *path = [UIBezierPath bezierPath]; 
     [path moveToPoint:[[pointsArray objectAtIndex:0] CGPointValue]]; 
     for (int x = 1; x < [pointsArray count]; x++) { 
      [path addLineToPoint:[[pointsArray objectAtIndex:x] CGPointValue]]; 
     } 
     [path closePath]; // Implicitly does a line between p4 and p1 
     [path fill]; // If you want it filled, or... 
     [path stroke]; // ...if you want to draw the outline. 
    } 
} 

-(void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx { 
    NSLog(@"drawLayer");// It's never called, i don't know why 
} 

- (void) initVariables { 
    pointsArray = [[NSMutableArray alloc] init]; 
} 

- (void) addNewPoints:(CGPoint)newPoint { 
    [pointsArray addObject:[NSValue valueWithCGPoint:newPoint]]; 
} 

@end 

,이 코드를 사용하고 있습니다 :

self.layer.backgroundColor = [UIColor whiteColor].CGColor; 
    self.layer.cornerRadius = 20.0; 
    self.layer.frame = CGRectInset(self.layer.frame, 0, 0); 

    for (PlansClass *pclass in layersContent) { 
     CALayerBezierPath *sublayer = [CALayerBezierPath layer]; 
     [sublayer initVariables]; 

     NSDictionary* json = [pclass.listOfPoints objectFromJSONString]; 

     float largerX = 0; float largerY = 0; 
     float smallerX = 10000; float smallerY = 10000; 

     for (NSDictionary *dic in json) { 

      [sublayer addNewPoints:CGPointMake([[[json objectForKey:dic] objectForKey:@"x"] floatValue], [[[json objectForKey:dic] objectForKey:@"y"] floatValue])]; 

      if (largerX < [[[json objectForKey:dic] objectForKey:@"x"] floatValue]) { 
       largerX = [[[json objectForKey:dic] objectForKey:@"x"] floatValue]; 
      } 

      if (smallerX > [[[json objectForKey:dic] objectForKey:@"x"] floatValue]) { 
       smallerX = [[[json objectForKey:dic] objectForKey:@"x"] floatValue]; 
      } 

      if (largerY < [[[json objectForKey:dic] objectForKey:@"y"] floatValue]) { 
       largerY = [[[json objectForKey:dic] objectForKey:@"y"] floatValue]; 
      } 

      if (smallerY > [[[json objectForKey:dic] objectForKey:@"y"] floatValue]) { 
       smallerY = [[[json objectForKey:dic] objectForKey:@"y"] floatValue]; 
      } 
     } 
     sublayer.frame = CGRectMake(smallerX, smallerY, largerX - smallerX, largerY - smallerY); 
     sublayer.backgroundColor = [UIColor redColor].CGColor; 
     [self.layer addSublayer:sublayer]; 
     [sublayer setNeedsDisplay]; 
    } 

을 문제는 앱 점심 식사 때마다 다음과 같은 오류가 발생합니다.

2012-09-13 08:05:47.648 abcd[20744:707] CALayerBezierPath - drawInContext 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSetFillColorWithColor: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSetStrokeColorWithColor: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSaveGState: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSetFlatness: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextAddPath: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextDrawPath: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextRestoreGState: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSaveGState: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSetLineWidth: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSetLineJoin: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSetLineCap: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSetMiterLimit: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextSetFlatness: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextAddPath: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextDrawPath: invalid context 0x0 
Sep 13 08:05:47 ipad-5 abcd[20744] <Error>: CGContextRestoreGState: invalid context 0x0 

또한, 나는 drawInContext 방법에 NSLogctx을 시도하고 그것은 나에게주는이 : 문제는 어디

는

2012-09-13 08:05:47.650 abcd[20744:707] <CGContext 0x15d950> 

그래서, 왜 내가 왜이 할 수있는 문맥이 무효입니다 내 맞춤 설정에 그리지 마십시오 CALayer?

Answer 1

문제는 컨텍스트를 푸시하지 않았 음을 나타냅니다. ctx, 푸시 중입니다. & pop. 그래서 해결책은 drawInContext

UIGraphicsPushContext(ctx); 

모든 일에 if 문에이 줄을 넣는 것만 큼 간단합니다.