在圖片上繪製出 文字的效果，可用以下程式碼：

- ( UIImage *)createShareImage:(NSString *)str

{

UIImage *image = [UIImageimageNamed:@"1.jpg"];

CGSize size=CGSizeMake(image.size.width,image.size.height);// 畫布大小

UIGraphicsBeginImageContextWithOptions(size,NO , 0.0 );

    [image drawAtPoint :CGPointMake (0,0)];

// 獲得一個位圖圖形上下文

CGContextRef

CGContextDrawPath (context,kCGPathStroke );

// 繪製文字

    [str drawAtPoint :CGPointMake (30 ,image.size.height *0.55) withAttributes :@{NSFontAttributeName :[UIFontfontWithName :@"Arial-BoldMT"size :40 ],NSForegroundColorAttributeName :[UIColorwhiteColor ]} ];

//

UIImage *newImage=UIGraphicsGetImageFromCurrentImageContext ();

UIGraphicsEndImageContext ();

//返回你的圖形

return newImage;

}

效果如下:

有時候需要截圖的效果程式碼如下 ：

//點選螢幕出發事件:

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event

{

// 1.開啟圖形上下文

CGSize imageSize = self.view.bounds.size;

UIGraphicsBeginImageContextWithOptions

// 2.將某個view的所有內容渲染到圖形上下文中

CGContextRef context = UIGraphicsGetCurrentContext();

    [self.view.layerrenderInContext:context];

// 3.取得圖片

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

CGImageRef subimageRef = CGImageCreateWithImageInRect(image.CGImage, CGRectMake(0, 0, 640, 480));

UIImage *subImage = [UIImageimageWithCGImage:subimageRef];

    [UIImagePNGRepresentation(subImage) writeToFile:@"/Users/apple/Desktop/view.png"atomically:YES];

// 4.關閉上下文

UIGraphicsEndImageContext();

}