遇到這個(gè)問題了，自然明白.....

• 起初，只是旋轉(zhuǎn)了imageView，image并沒有真正旋轉(zhuǎn)，代碼如下：

    double Degree=45.0/180.0;
    CGAffineTransform transform= CGAffineTransformMakeRotation(-M_PI* Degree);
    bgimgView.transform = transform;//旋轉(zhuǎn)bgimgView，沒有旋轉(zhuǎn)到bgimgView.image

• 拿到旋轉(zhuǎn)后的image(致敬開源精神的大佬)：

+ (UIImage *)ehs_imageWithRotation:(UIImage *)image rotationDegree:(CGFloat)degree
{
    //將image轉(zhuǎn)化成context
    //獲取圖片像素的寬和高
    size_t width =  image.size.width * image.scale;
    size_t height = image.size.height * image.scale;
    
    //顏色通道為8 因?yàn)?-255 經(jīng)過了8個(gè)顏色通道的變化
    //每一行圖片的字節(jié)數(shù) 因?yàn)槲覀儾捎玫氖茿RGB/RGBA 所以字節(jié)數(shù)為 width * 4
    size_t bytesPerRow =width * 4;
    //圖片的透明度通道
    CGImageAlphaInfo info =kCGImageAlphaPremultipliedFirst;
    CGContextRef context = CGBitmapContextCreate(nil, width, height, 8, bytesPerRow, CGColorSpaceCreateDeviceRGB(), kCGBitmapByteOrderDefault|info);
    
    if (!context) {
        return nil;
    }
    //將圖片渲染到圖形上下文中
    CGContextDrawImage(context, CGRectMake(0, 0, width, height), image.CGImage);
    
    //旋轉(zhuǎn)context
    uint8_t* data =(uint8_t*) CGBitmapContextGetData(context);
    //旋轉(zhuǎn)欠的數(shù)據(jù)
    vImage_Buffer src = { data,height,width,bytesPerRow};
    //旋轉(zhuǎn)后的數(shù)據(jù)
    vImage_Buffer dest= { data,height,width,bytesPerRow};
    
    //背景顏色
    Pixel_8888  backColor = {0,0,0,0};
    //填充顏色
    vImage_Flags flags = kvImageBackgroundColorFill;
    
    vImageRotate_ARGB8888(&src, &dest, nil, degree * M_PI/180.f, backColor, flags);
    
    //將conetxt轉(zhuǎn)換成image
    CGImageRef imageRef = CGBitmapContextCreateImage(context);
    UIImage  * rotateImage =[UIImage imageWithCGImage:imageRef scale:image.scale orientation:image.imageOrientation];
    
    return  rotateImage;
}