Question

我为此UITabBar设置了自定义指标图片

UIImage *tabBarSelectedImage = [[UIImage imageNamed:@"tabBar_selected"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 0, 0, 0)];
[[UITabBar appearance] setSelectionIndicatorImage:tabBarSelectedImage];

并在tabBarSelectedImage周围获得4px填充。是否可以将填充设置为0px？这样我的tabBarSelectedImage填满整个空间，没有边框可见？

Answer 1

这是你的问题的解决方案......我实际上并没有这样做......我正在做其他的事情，但下面的代码会帮助你很多......首先我告诉你我做了什么......

我制作了UITabbar的类别并在其中实现了以下方法

- (void)recolorItemsWithColor:(UIColor *)color shadowColor:(UIColor *)shadowColor 
shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur
{
CGColorRef cgColor = [color CGColor];
CGColorRef cgShadowColor = [shadowColor CGColor];
for (UITabBarItem *item in [self items]) {

if ([item respondsToSelector:@selector(selectedImage)] &&
    [item respondsToSelector:@selector(setSelectedImage:)] &&
    [item respondsToSelector:@selector(_updateView)])
{
    CGRect contextRect;
    contextRect.origin.x = 0.0f;
    contextRect.origin.y = 0.0f;

    //instead of following line you can give our own desired size of contextRect. 
    //just change the method parameters and include a parameter of desired size in it.
    // and this desired size would be the tabbarbutton size...so you will pass the size of 
    // you tabbarbutton here...because on the back of image there is a tabbarbutton and if
    // set the image of button size it will occupy whole the are of button.

    contextRect.size = desired size //[[item selectedImage] size];
    // Retrieve source image and begin image context
    UIImage *itemImage = [item image];
    CGSize itemImageSize = [itemImage size];

    CGPoint itemImagePosition; 
    itemImagePosition.x = ceilf((contextRect.size.width - itemImageSize.width) / 2);
    itemImagePosition.y = ceilf((contextRect.size.height - itemImageSize.height) / 2);
    UIGraphicsBeginImageContext(contextRect.size);
    CGContextRef c = UIGraphicsGetCurrentContext();

    // Setup shadow
    CGContextSetShadowWithColor(c, shadowOffset, shadowBlur, cgShadowColor);

    // Setup transparency layer and clip to mask
    CGContextBeginTransparencyLayer(c, NULL);
    CGContextScaleCTM(c, 1.0, -1.0);
    CGContextClipToMask(c, CGRectMake(itemImagePosition.x, -itemImagePosition.y,
    itemImageSize.width, -itemImageSize.height), [itemImage CGImage]);

    // Fill and end the transparency layer
    CGContextSetFillColorWithColor(c, cgColor);
    contextRect.size.height = -contextRect.size.height;
    CGContextFillRect(c, contextRect);
    CGContextEndTransparencyLayer(c);


    // Set selected image and end context
    [item setSelectedImage:UIGraphicsGetImageFromCurrentImageContext()];
    UIGraphicsEndImageContext();
    // Update the view
    [item _updateView];
   }
   }

   }

现在我在我的自定义类UITabbarController中调用了上面的方法...我重写了方法
-(void)setSelectedIndex:(NSUInteger)selectedIndex并在该方法中执行了以下操作。

  -(void)setSelectedIndex:(NSUInteger)selectedIndex {
       self.selectedViewController = [self.viewControllers objectAtIndex:selectedIndex];
       NSLog(@"selectedIndex:%d, totalCount:%d",selectedIndex,[self.tabBar.subviews count]);
   for (uint i=1; i < [self.tabBar.subviews count]; i++)
   {
      UIView *view = [self.tabBar.subviews objectAtIndex:i];
      NSLog(@"class:%@",NSStringFromClass([view class]));
   if ([NSStringFromClass([view class]) isEqualToString:@"UITabBarButton"])
   {
    //view.frame = CGRectMake(view.frame.origin.x, view.frame.origin.y,  
    view.frame.size.width, self.tabBar.frame.size.height);
      NSLog(@"selectedIndex:%d,i:%d",self.selectedIndex,i);
    if (self.selectedIndex+1==i) {
        [self.tabBar recolorItemsWithColor:[UIColor whiteColor] shadowColor:[UIColor 
                            blackColor] shadowOffset:view.frame.size shadowBlur:0.5];

    }
    } 
    }

    }

您可以优化代码以避免进行类别或子类化......但为此您必须抓住目标C.如果有任何问题，您可以告诉我。干杯

Answer 2

我找到了一种更简单的解决方案：

self.tabBar.frame = CGRectInset(self.tabBar.frame,0,-6);

Answer 3

好吧，我在这里发现的是，只有在使用可调整大小的图像时才会出现填充。使用不可调整大小的图像时，填充不存在。

因此，一个可能的解决方案是子类UITabBar并在项目大小改变时配置selectionIndicatorImage。

@interface TKTabBar

@end

@implementation TKTabBar
{
    CGSize _selectionIndicatorImageSize;
}

- (void)tk_refreshSelectionIndicatorImageForItemSize:(CGSize)itemSize
{
    // Recompute the selection indicator image only if the size of the item has changed.
    if (!CGSizeEqualToSize(itemSize, _selectionIndicatorImageSize))
    {
        _selectionIndicatorImageSize = itemSize;

        // Compute here the new image from the item size.
        // In this example I'm using a Cocoa Pod called UIImage+Additions to generate images dynamically.

        UIImage *redImage = [UIImage add_imageWithColor:[UIColor add_colorWithRed255:208 green255:75 blue255:43] size:CGSizeMake(itemSize.width, 2)];
        UIImage *clearImage = [UIImage add_imageWithColor:[UIColor clearColor] size:CGSizeMake(itemSize.width, itemSize.height)];
        UIImage *mixImage = [clearImage add_imageAddingImage:redImage offset:CGPointMake(0, itemSize.height-2)];

        // Finally, I'm setting the image as the selection indicator image.
        [self setSelectionIndicatorImage:mixImage];
    }
}

// Using the layout subviews method to detect changes on the tab size
- (void)layoutSubviews
{
    [super layoutSubviews];

    // Only needed if at least one item
    if (self.items.count > 0)
    {
        CGSize itemSize = CGSizeZero;

        // Iterating over all subviews
        for (UIView *view1 in self.subviews)
        {
            // Searching for "UITabBarButtons"
            if ([view1 isKindOfClass:NSClassFromString(@"UITabBarButton")])
            {
                itemSize = view1.bounds.size;
                break;
            }
        }

        // Applying the new item size
        [self tk_refreshSelectionIndicatorImageForItemSize:itemSize];
    }
}

@end

Answer 4

首先，setSelectionIndicatorImage至[UIColor clearColor]
其次，之前将任何视图控制器添加到tabbarcontroller，将图像作为子视图添加到标签栏。然后它将显示在tabbaritems下作为指标图像
实施tabbarcontroller delegate方法以更改图像的位置。

我已经实现了这种方式，它完美无缺。如果你想为不同的方向调整tabbar的大小，你应该稍微调整一下。您可以继承UITabbarController并实施layoutSubview方法。

UITabBar selectionIndicatorImage填充

4 个答案: