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!");
            }
        }
    }