iOS实现截屏 并合适保存

开发游戏时，往往会有这么一个需求：在某个成就达成或者破纪录时，需要截个屏，然后发送到微博上与好友/粉丝分享，虽然home ＋ 开机键组合可手动截屏，在Cocos2d有个CCRenderTexture类，借助该类可很容易实现代码截取功能。使用CCRenderTexture，我们可以截取游戏场景、某个Layer，甚至是精灵：

 /**游戏截图
  *@param node 需要截取的控件
 */
 - (void)snapshotScreen:(CCNode*)node
 {
     //取得屏幕大小
     CGSize winSize = [[CCDirector sharedDirector]winSize];
     CCRenderTexture* renderTexture = [CCRenderTexture renderTextureWithWidth:winSize.width
                                                                       height:winSize.height];
     [renderTexture begin];
     [node visit];
     [renderTexture end];
     [renderTexture cleanup];
     UIImage *snapshot = [renderTexture getUIImageFromBuffer];
     //把截图保存到相册里
     UIImageWriteToSavedPhotosAlbum(snapshot, nil, nil, nil);
 }

  

如果游戏支持高清模式，上面代码截出来的图是960 * 640大小的，这个尺寸如果要上传到微博上，文件的大小可能会超出限制，那么在上传前可用先把截图大小缩小点如480*320，以减少图片体积：

 /** 调整图片大小*/
 - (UIImage *) scaleFromImage: (UIImage *) image toSize: (CGSize) size
 {
     UIGraphicsBeginImageContext(size);
     [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
     UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
     UIGraphicsEndImageContext();
     return newImage;
 }

  

同时可以保存

 保存文件

 UIImage *m_imgFore=......;

 //png格式

 NSData *imagedata=UIImagePNGRepresentation(m_imgFore);

 //JEPG格式

 //NSData *imagedata=UIImageJEPGRepresentation(m_imgFore,1.0);

 NSArray*paths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);

 NSString *documentsDirectory=[paths objectAtIndex:0];

 NSString *savedImagePath=[documentsDirectorystringByAppendingPathComponent:@"saveFore.png"];

 [imagedata writeToFile:savedImagePath atomically:YES];

 或者

 [fileManager createFileAtPath:[filePath stringByAppendingString:@"/image.png"] contents:data attributes:nil];    将图片保存为PNG格式

  [fileManager createFileAtPath:[filePath stringByAppendingString:@"/image.jpg"] contents:data attributes:nil];   将图片保存为JPEG格式

如果不是cocos2D开发，则使用如下代码：

方法1：

 -(void)screenShots
 {
     CGSize imageSize = [[UIScreen mainScreen] bounds].size;
     if (NULL != UIGraphicsBeginImageContextWithOptions) {
         UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
     }
     else
     {
         UIGraphicsBeginImageContext(imageSize);
     }

     CGContextRef context = UIGraphicsGetCurrentContext();

     for (UIWindow * window in [[UIApplication sharedApplication] windows]) {
         if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen]) {
             CGContextSaveGState(context);
             CGContextTranslateCTM(context, [window center].x, [window center].y);
             CGContextConcatCTM(context, [window transform]);
             CGContextTranslateCTM(context, -[window bounds].size.width*[[window layer] anchorPoint].x, -[window bounds].size.height*[[window layer] anchorPoint].y);
             [[window layer] renderInContext:context];

             CGContextRestoreGState(context);
         }
     }

     UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

     UIGraphicsEndImageContext();
     UIImageWriteToSavedPhotosAlbum(image, self, nil, nil);
     NSLog(@"Suceeded!");
 }

(注意：方法1截图后会是竖屏，所以需要配合UIImage旋转的方法判断方向后旋转才能合适保存，见文章旋转翻转UIImage 不是UIImageView 适用于源图像的处理，例如截图后旋转)

所以再提供另外一方法：

方法2

 UIView *view = [[[[[UIApplication sharedApplication] windows] objectAtIndex:1] subviews] lastObject];//获得某个window的某个subView

     NSInteger index = 0;//用来给保存的png命名
     for (UIView *subView in [view subviews]) {//遍历这个view的subViews
         if ([subView isKindOfClass:NSClassFromString(@"UIImageView")] || [subView isKindOfClass:NSClassFromString(@"UIThreePartButton")]) {//找到自己需要的subView
             //支持retina高分的关键
             if(UIGraphicsBeginImageContextWithOptions != NULL)
             {
                 UIGraphicsBeginImageContextWithOptions(subView.frame.size, NO, 0.0);
             } else {
                 UIGraphicsBeginImageContext(subView.frame.size);
             }

             //获取图像
             [subView.layer renderInContext:UIGraphicsGetCurrentContext()];
             UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
             UIGraphicsEndImageContext();

             //保存图像
             NSString *path = [NSHomeDirectory() stringByAppendingFormat:@"/%d.png",index];
             if ([UIImagePNGRepresentation(image) writeToFile:path atomically:YES]) {
                 index += 1;
                 NSLog(@"Succeeded!");
             }
             else {
                 NSLog(@"Failed!");
             }
         }
     }