+(UIImage *)screenForView:(UIView *)view{// UIGraphicsBeginImageContext(view.frame.size);// CGContextRef context = UIGraphicsGetCurrentContext();// [view.layer renderInContext:context];// UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();// UIGraphicsEndImageContext();//// return theImage;size_t width = view.frame.size.width;size_t height = view.frame.size.height;size_t bitsPerComponent = 8; //这个我不太懂,大概意思是表示一个颜色职的位数size_t bytesPerRow = width * 4; //每一行的字节数，ARGB 每一个位数是8，也就是一个字节 ,每一个像索占4个字节CGColorSpaceRef spaceRef = CGColorSpaceCreateDeviceRGB(); //这个命名空间和灰度化有关系void * data = http://www.mamicode.com/malloc(bytesPerRow * height); //文档上有说明CGContextRef context = CGBitmapContextCreate(data, width, height, bitsPerComponent, bytesPerRow, spaceRef, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);if (context == NULL) {NSLog(@"创建绘图环境失败");}//旋转画面//先翻转画布 — 仿射距阵很让人纠结，之后我会写一篇关于仿射距阵的文章CGContextTranslateCTM(context, width, 0);CGContextScaleCTM(context, -1, 1);CGContextTranslateCTM(context, width, height);CGContextRotateCTM(context, radians(-180.0));//到目前为卡，坐标旋转的和ios的坐标一至了CGContextSaveGState(context);//保存当前的状态CGContextClearRect(context, CGRectMake(0, 0, width, height));// CGContextSetFillColorWithColor(context, [[UIColor blackColor] CGColor]);// CGContextFillRect(context, CGRectMake(0, 0, width, height));//CGContextClipToRect(context, CGRectMake(0, 0, width, height));[[view layer] renderInContext:context]; //配送到这个context//添加水印//变化坐标，frame在这里没有用CGContextTranslateCTM(context, 220, height-50-10);UILabel * label = [[UILabel alloc]initWithFrame:CGRectMake(0, height-50, 100, 50)];label.text = @"惟愿";[label setShadowColor:[UIColor grayColor]];[label setTextColor:[UIColor whiteColor]];[label setBackgroundColor:[UIColor clearColor]];[label setFont:[UIFont boldSystemFontOfSize:20]];[label setTextAlignment:NSTextAlignmentCenter];[[label layer] renderInContext:context];[label release];//添加水印2CGContextTranslateCTM(context, 0, 40);UILabel * label2 = [[UILabel alloc]initWithFrame:CGRectMake(0, height-50, 100, 10)];label2.text = @"http:/onlywish.me";[label2 setShadowColor:[UIColor grayColor]];[label2 setTextColor:[UIColor whiteColor]];[label2 setBackgroundColor:[UIColor clearColor]];[label2 setFont:[UIFont boldSystemFontOfSize:12]];[label2 setTextAlignment:NSTextAlignmentCenter];[[label2 layer] renderInContext:context];[label2 release];CGImageRef imageRef = CGBitmapContextCreateImage(context);UIImage * result = [UIImage imageWithCGImage:imageRef];//释放内存CGColorSpaceRelease(spaceRef);CGImageRelease(imageRef);CGContextRelease(context);free(data);return result;}