如何使用NSString绘制功能从文本创建UIImage [英] How do I use the NSString draw functionality to create a UIImage from text

问题描述

我想在 UIImage 中绘制 NSString 变量的内容，但我绝对不知道这个怎么做。我需要编写一个接收 NSString 作为参数的方法，并返回一个带有文本的 UIImage 。

I would like to draw the content of a NSString variable in a UIImage, but I have absolutely no idea how to do this. I need to write a method that would receive a NSString as parameter and return a UIImage with the text drawn into it.

推荐答案

你可以试试这个:(针对iOS 4更新）

You can try this: (updated for iOS 4)

-(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;
}

要拨打电话：

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

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