iphone - 如何使用 NSString 绘制功能从文本创建 UIImage

Question

我想在UIImage中绘制NSString变量的内容，但我完全不知道如何做到这一点。我需要编写一个方法，该方法将接收 NSString 作为参数，并返回一个包含绘制到其中的文本的 UIImage 。

Answer 1

您可以尝试以下操作:(针对 iOS 4 进行了更新)

-(UIImage *)imageFromText:(NSString *)text
{
    // set the font type and size
    UIFont *font = [UIFont systemFontOfSize:20.0];  
    CGSize size  = [text sizeWithFont:font];

    // check if UIGraphicsBeginImageContextWithOptions is available (iOS is 4.0+)
    if (UIGraphicsBeginImageContextWithOptions != NULL)
        UIGraphicsBeginImageContextWithOptions(size,NO,0.0);
    else
        // iOS is < 4.0 
        UIGraphicsBeginImageContext(size);

    // optional: add a shadow, to avoid clipping the shadow you should make the context size bigger 
    //
    // CGContextRef ctx = UIGraphicsGetCurrentContext();
    // CGContextSetShadowWithColor(ctx, CGSizeMake(1.0, 1.0), 5.0, [[UIColor grayColor] CGColor]);

    // draw in context, you can use also drawInRect:withFont:
    [text drawAtPoint:CGPointMake(0.0, 0.0) withFont:font];

    // transfer image
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();    

    return image;
}

调用它:

UIImage *image = [self imageFromText:@"This is a text"];