iOS 15 新特性适配

1、导航栏的性能做了优化，默认情况下，如果导航栏与视图没有折叠，导航栏的背景透明，如果系统检测到有重叠的话，会变成毛玻璃的效果

if (@available(iOS 13.0, *)) {
        UINavigationBarAppearance *appearance = [[UINavigationBarAppearance alloc] init];
        [appearance setShadowImage:[[UIImage alloc] init]];
        [appearance setBackgroundColor:TAD_THM.navigationBackgroundColor];
        // 隐藏分割线 设置一个透明或者纯色的图片 设置nil 或者 [UIImage new]无效
        [appearance setBackgroundImage:[UIImage zt_imageWithPureColor:[UIColor whiteColor]]];
        [appearance setShadowImage:[UIImage zt_imageWithPureColor:[UIColor whiteColor]]];
        [[UINavigationBar appearance] setScrollEdgeAppearance: appearance];
}

颜色转图片

+ (UIImage *)zt_imageWithPureColor:(UIColor *)color {
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(3, 3), NO, [UIScreen mainScreen].scale);
    UIBezierPath* p = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, 3, 3)];
    [color setFill];
    [p fill];
    UIImage* img = UIGraphicsGetImageFromCurrentImageContext();
    return img;
}
+ (UIImage *)zt_imageWithPureColor:(UIColor *)color size:(CGSize )size{
    UIGraphicsBeginImageContextWithOptions(size, NO, [UIScreen mainScreen].scale);
    UIBezierPath* p = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, size.width, size.height)];
    [color setFill];
    [p fill];
    UIImage* img = UIGraphicsGetImageFromCurrentImageContext();
    return img;
}

2、UITableView新增了一条新属性：sectionHeaderTopPadding， 默认会给每一个section header 增加一个高度，当我们使用 UITableViewStylePlain 初始化UITableView的时候，能发现sectionHeader增高了22px。解决办法就是手动去除这个高度

if (@available(iOS 15.0, *)) {
    table.sectionHeaderTopPadding = 0;
}

3、UIImageWriteToSavedPhotosAlbum存储图片之后的回调不再返回图片了，会返回nil，如果在回调方法里面操作image有可能会直接Crash，目前的解决办法声明一个全局image去记录，后面再去操作

self.image = image;
UIImageWriteToSavedPhotosAlbum(image,self,@selector(image:didFinishSavingWithError:contextInfo:), NULL);
            
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo{
    // self.image doing...
}