iOS TabBar图像分配 [英] iOS TabBar Image assignment

问题描述

如果可能，您将如何将自定义图像设置为标签栏项目的每个状态（已选择/未选中）。这将需要覆盖默认行为，该行为在选中时使选项卡条项目图像变蓝，并在未选中时将其变灰。谢谢。

If it is possible, how would you go about setting a custom image to each state (selected/not selected) of tab bar items. This would need to override the default behavior which blues the tab bar item image when selected and grays it when not selected. Thanks.

推荐答案

要重新着色标签栏项目使用 -

To recolor tab bar item use -

/* for colored tab items */

@interface UITabBar (ColorExtensions)
- (void)recolorItemsWithColor:(UIColor *)color shadowColor:(UIColor *)shadowColor shadowOffset:(CGSize)shadowOffset shadowBlur:(CGFloat)shadowBlur;
@end

@interface UITabBarItem (Private)
@property(retain, nonatomic) UIImage *selectedImage;
- (void)_updateView;
@end

@implementation UITabBar (ColorExtensions)

- (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;
            contextRect.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]);

        /*  //Setup the gradient... 
            CGFloat components[8] = {0.0,0.4,1.0,0.2,0.0,0.6,1.0,1.0};
            CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();  
            CGGradientRef colorGradient = CGGradientCreateWithColorComponents(colorSpace, components, NULL, 2);
            CGContextDrawLinearGradient(c, colorGradient,CGPointZero,CGPointMake(0,contextRect.size.height),0);
        */  

            // 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];



        }

}

@end


/* colored tab items code completed */

然后在app delegate中使用 -

then in app delegate use -

[[tabbarcontroller tabBar] recolorItemsWithColor:[UIColor colorWithRed:0.6640 green:0.1992 blue:0.1992 alpha:1.0] shadowColor:[UIColor clearColor] shadowOffset:CGSizeMake(0.0f, -1.0f) shadowBlur:3.0f];

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