在UITextView上滚动内部阴影

我想要UITextView的子类能够用自定义边框加顶部+左侧内部阴影来绘制圆形矩形。在UITextView上滚动内部阴影

我在创建此效果（通过阅读this后）获得任何（静态边界）视图的巨大成功，但有滚动视图的问题。

这个效果我做我的自定义类的-setFrame实例方法：

- (void)setFrame:(CGRect)frame { 
[super setFrame:frame]; 

UIColor *borderColor = [UIColor colorWithRed:BORDER_COLOR_RED green:BORDER_COLOR_GREEN blue:BORDER_COLOR_BLUE alpha:BORDER_COLOR_ALPHA]; 

// Store index of the shadow sublayer for future use 
[self setShadowLayerIndex:[LayerFormatter formatAsRoundRectWithShadowOn:self withBackgroundColor:[UIColor whiteColor] andBorderColor:borderColor]];}

formatAsRoundRectWithShadowOn：是定义为类方法：

+(NSUInteger)formatAsRoundRectWithShadowOn:(UIView*)view withBackgroundColor:(UIColor *)backgroundColor andBorderColor:(UIColor *)borderColor { 
if([view isKindOfClass:[UITextField class]]) 
    ((UITextField*)view).borderStyle = UITextBorderStyleNone; 
view.backgroundColor = backgroundColor; 

view.layer.borderWidth = 1.0; 
view.layer.borderColor = [borderColor CGColor]; 
view.layer.cornerRadius = CORNER_RADIUS; 
view.layer.masksToBounds = YES; 

//Add some insets to the text: https://stackoverflow.com/a/4423805 
UIView *paddingView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 5, 20)]; 

if([view isKindOfClass:[UITextField class]]) 
{ 
    ((UITextField*)view).leftView = paddingView; 
    ((UITextField*)view).leftViewMode = UITextFieldViewModeAlways; 
} 

// Create and apply a shadow layer. Help here: https://stackoverflow.com/questions/4431292/inner-shadow-effect-on-uiview-layer 
CAShapeLayer* shadowLayer = [CAShapeLayer layer]; 

[shadowLayer setFrame:view.bounds]; 
[shadowLayer setShadowColor:[[UIColor blackColor] CGColor]]; 
[shadowLayer setShadowRadius:3.0f]; 
[shadowLayer setShadowOpacity:0.35f]; 
[shadowLayer setShadowOffset:CGSizeMake(2.0f, 2.0f)]; 

[shadowLayer setFillColor:[backgroundColor CGColor]]; 

// Causes the inner region in this example to NOT be filled. 
[shadowLayer setFillRule:kCAFillRuleEvenOdd]; 

// Create inner and outer rectangle paths. 
CGMutablePathRef path = CGPathCreateMutable(); 

// Outer path should be bigger than the field 
UIBezierPath *bpOuter = [UIBezierPath bezierPathWithRect:CGRectInset(shadowLayer.bounds, -10, -10)]; 

// Inner path is the visible part of the view 
UIBezierPath *bpInner = [UIBezierPath bezierPathWithRoundedRect:shadowLayer.bounds cornerRadius:CORNER_RADIUS]; 

// Add outer path and then add the inner path so it's subtracted from the outer path. 
CGPathAddPath(path, NULL, bpOuter.CGPath); 
CGPathAddPath(path, NULL, bpInner.CGPath); 

CGPathCloseSubpath(path); 

[shadowLayer setPath:path]; 
CGPathRelease(path); 

[[view layer] addSublayer:shadowLayer]; 

NSUInteger addedAtIndex = [[[view layer] sublayers] indexOfObject:shadowLayer]; 
return addedAtIndex;}

要正确处理阴影+边框显示器当文字视图滚动我使用我的自定义类-setBounds方法来更新阴影层框架：

-(void)setBounds:(CGRect)bounds{ 
[super setBounds:bounds]; 

// Change the frame of the shadow layer to reflect new bounds 
[[[[self layer] sublayers] objectAtIndex:self.shadowLayerIndex] setFrame:bounds];}

我遇到的问题是在向下滚动时（插入新的文本行时）或顶部（滚动到文本的开头处）时底部的阴影+框架绘制不正确。

插入新行或滚动完成后（视图再次为静态），视图绘制正确。

对这个问题的任何见解都非常值得欢迎。

来源

2012-11-30 kr45ko

我有一段时间来深入研究这个问题，并找到了我想要分享的解决方案。

起初我意识到最好在-awakeFromNib而不是-setFrame中设置阴影层。

当文本视图滚动时处理正确的阴影+边框显示我已经改变了这样的方法：更新阴影层我现在使用-layoutSubviews覆盖在我的自定义类中。在-layoutSubviews覆盖我重新创建阴影层尊重新的界限，然后调用[super layoutSubviews]。

滚动，改变方向 - 它就像一个魅力！

- (void)layoutSubviews 
{ 
    [self updateShadow]; 
    [super layoutSubviews]; 
} 

- (void)updateShadow 
{ 
    if (shadowLayer) 
     [shadowLayer removeFromSuperlayer]; 

    shadowLayer = [LayerFormatter addInnerShadowLayerOn:self withShadowColor:[UIColor blackColor]]; 
}

注意+(NSUInteger)formatAsRoundRectWithShadowOn:(UIView*)view withBackgroundColor:(UIColor *)backgroundColor andBorderColor:(UIColor *)borderColor现在返回层参考视图的层层次中已经添加层（返工很简单）：

+(CAShapeLayer *)addInnerShadowLayerOn:(UIView *)view withShadowColor:(UIColor *)shadowColor;

任何证据/意见，这种做法是正确的，而不是只是工作将不胜感激。

来源

2013-01-29 15:24:36 kr45ko

在UITextView上滚动内部阴影

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