随笔待整理

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#import "UINavigationBar+ChangeColor.h"

@implementation UINavigationBar (ChangeColor)

- (void)start{

    UIImageView *shawImage = [self findNavLineImageOn:self];

    shawImage.hidden = YES;

    self.translucent = YES;

}

- (void)reset{

    UIImageView *shawImage = [self findNavLineImageOn:self];

    shawImage.hidden = NO;

    [self setBackgroundImage:nil forBarMetrics:UIBarMetricsDefault];

    self.translucent = NO;

}

- (void)changeColor:(UIColor *)color withScrollView:(UIScrollView *)scrollView andValud:(CGFloat)value{

    if (scrollView.contentOffset.y < 0) {

        //下拉时导航隐藏

        self.hidden = YES;

    }else{

        self.hidden = NO;

        //计算透明度

        CGFloat alpha = scrollView.contentOffset.y /value > 1.0f ? 1 : scrollView.contentOffset.y/value;

        //设置颜色改为图片

        UIImage *image = [self imageWithColor:[color colorWithAlphaComponent:alpha]];

        [self setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];

        self.translucent = alpha >=1.0f ? NO : YES;

    }

}

- (UIImageView *)findNavLineImageOn:(UIView *)imageView{

    if ([imageView isKindOfClass:[UIImageView class]] && imageView.frame.size.height <=1.0) {

        return (UIImageView *)imageView;

    }

    for (UIView *subViews in imageView.subviews) {

        UIImageView *imageView = [self findNavLineImageOn:subViews];

        if (imageView) {

            return imageView;

        }

    }

    return nil;

}

#pragma mark - Color To Image

- (UIImage *)imageWithColor:(UIColor *)color {

    //创建1像素区域并开始图片绘图

    CGRect rect = CGRectMake(0, 0, 1, 1);

    UIGraphicsBeginImageContext(rect.size);

    //创建画板并填充颜色和区域

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);

    CGContextFillRect(context, rect);

    //从画板上获取图片并关闭图片绘图

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return image;

}

@end

随笔待整理

标签：begin   dde   app   获取   graph   and   nil   sel   隐藏   

原文地址：https://www.cnblogs.com/TheYouth/p/9300318.html