UIView灰度。图中不被重绘

我设法通过添加以下视图顶部得到的灰阶一个UIView：UIView灰度。图中不被重绘

@interface GreyscaleAllView : UIView 

@property (nonatomic, retain) UIView *underlyingView; 

@end 

@implementation GreyscaleAllView 

@synthesize underlyingView; 

- (void)drawRect:(CGRect)rect { 

    CGContextRef context = UIGraphicsGetCurrentContext(); 

    // draw the image 
    [self.underlyingView.layer renderInContext:context]; 

    // set the blend mode and draw rectangle on top of image 
    CGContextSetBlendMode(context, kCGBlendModeColor); 
    CGContextSetRGBFillColor(context, 0.0, 0.0, 0.0, 1.0); 
    CGContextFillRect(context, rect); 
    [super drawRect:rect]; 
} 

@end

它的工作原理，但内容没有更新，除非我手动调用setNeedsDisplay。（我可以按一个UIButton并且动作会触发，但外观没有任何变化）因此，为了表现得像预期的那样，我每秒调用setNeedsDisplay 60次。我究竟做错了什么？

UPDATE：

- (void)viewDidLoad { [super viewDidLoad]; GreyscaleAllView *grey = [[[GreyscaleAllView alloc] initWithFrame:self.view.frame] autorelease]; grey.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight; grey.userInteractionEnabled = NO; [self.view addSubview:grey]; }

我已经完成了这些垫层意见重绘：

inits与此OverlayView的的视图 - 控制

@implementation GreyscaleAllView 

- (void)setup { 

    self.userInteractionEnabled = FALSE; 
    self.contentMode = UIViewContentModeRedraw; 

    [self redrawAfter:1.0/60.0 repeat:YES]; 

} 

- (void)redrawAfter:(NSTimeInterval)time repeat:(BOOL)repeat { 

    if(repeat) { 
     // NOTE: retains self - should use a proxy when finished 
     [NSTimer scheduledTimerWithTimeInterval:time target:self selector:@selector(setNeedsDisplay) userInfo:nil repeats:YES]; 
    } 

    [self setNeedsDisplay]; 
}

来源

2012-05-10 jalmaas

做同样可以您是从初始化此灰度视图的位置添加代码？ – rishi

添加视图控制器初始化代码并重绘代码 – jalmaas

尝试使用GreyscaleAllView * grey = [[[GreyscaleAllView alloc] initWithFrame：CGRectMake（0,0,320,480）] autorelease]; – rishi

你真正想要的是什么仅当父视图重绘时才让子视图重绘，在这种情况下，您可以覆盖父v中的-setNeedsDisplay并在GreyscaleAllView上拨打-setNeedsDisplay。这需要继承UIView的UIViewController的view属性。在控制器

即实现loadView，并设置

self.view = [[CustomView alloc] initWithFrame:frame];

如上所述，其中CustomView覆盖setNeedsDisplay：

@implementation CustomView 

- (void)setNeedsDisplay 
{ 
    [grayView setNeedsDisplay]; // grayView is a pointer to your GreyscaleAllView 
    [super setNeedsDisplay]; 
} 

@end

为了完整起见，你也应该为-setNeedsDisplayInRect:

来源

2012-10-31 23:28:59 yfrancis

UIView灰度。图中不被重绘

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