保存当前view到相册

UIGraphicsBeginImageContext(currentView.bounds.size);     //currentView 当前的view
[currentView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);