view转image

-(NSImage*)viewToImage:(NSView*)view

{

    NSBitmapImageRep*bitmap =  [self bitmapImageRepForCachingDisplayInRect:[view visibleRect]];

    [view cacheDisplayInRect:[view visibleRect] toBitmapImageRep:bitmap];

    NSImage *image = [[NSImage alloc] initWithSize:NSMakeSize(view.bounds.size.width, view.bounds.size.height)];

    [image addRepresentation:bitmap];

    return image;

}