如何在iOS上将文本转换为图像? [英] How to convert text to Image on iOS?

问题描述

我正在尝试编写一个将文本字段文本转换为图像的函数(示例).我试图搜索一个示例，大多数示例也覆盖了图像上的文本.可以给我一些例子或提示该怎么做吗?

I am trying to write a function to convert the textfield text to an image (example). I have tried to search for an example, most of the sample also is overwrite text on image. Is it possible to give me some example or hints on how to do that?

推荐答案

可能有几种方法.

1. 如果您有一个现有的UITextField，UITextView或UILabel，您只想将其渲染为图像，则可以采用传统的快照方法，例如:

1. If you have an existing UITextField, UITextView or UILabel that you just want to render as an image, you can employ the traditional snapshot approaches, such as:

- (UIImage *)imageForView:(UIView *)view
{
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, 0);

    if ([view respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)])
        [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];  // if we have efficient iOS 7 method, use it ...
    else
        [view.layer renderInContext:UIGraphicsGetCurrentContext()];         // ... otherwise, fall back to tried and true methods

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

    return image;
}

如果您想使用通用的从文本创建图像"例程，则在iOS 7中，它看起来像是:

If you wanted a generic "create image from text" routine, in iOS 7, it would look like:

- (UIImage *)imageFromString:(NSString *)string attributes:(NSDictionary *)attributes size:(CGSize)size
{
    UIGraphicsBeginImageContextWithOptions(size, NO, 0);
    [string drawInRect:CGRectMake(0, 0, size.width, size.height) withAttributes:attributes];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

以上内容将创建一个图像，其大小将根据文本而有所不同.显然，如果只需要固定大小的图像，则使用常量frame而不是动态构建它.

The above will create an image whose size will vary based upon the text. Clearly, if you just want a fixed size image, then use constants frame, rather than dynamically building it.

无论如何，您都可以像这样使用上面的内容:

Anyway, you could then use the above like so:

NSString *string = @"Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";

NSDictionary *attributes = @{NSFontAttributeName            : [UIFont systemFontOfSize:20],
                             NSForegroundColorAttributeName : [UIColor blueColor],
                             NSBackgroundColorAttributeName : [UIColor clearColor]};

UIImage *image = [self imageFromString:string attributes:attributes size:self.imageView.bounds.size];

如果您需要支持早期的iOS版本，则可以使用以下技术:

If you need to support earlier iOS versions, you could use this technique:

- (UIImage *)imageFromString:(NSString *)string font:(UIFont *)font size:(CGSize)size
{
    UIGraphicsBeginImageContextWithOptions(size, NO, 0);
    [string drawInRect:CGRectMake(0, 0, size.width, size.height) withFont:font lineBreakMode: NSLineBreakByWordWrapping];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

每一个都有很多很多的排列.这仅取决于您要实现的目标.

There are many, many permutations of each of these. It just depends upon what you are trying to achieve.

另一种方法是在视图中同时具有UIImageView和UILabel/UITextView对象，如果您有来自服务器的图像，则设置UIImageView的图像，然后设置文本. UILabel/UITextView中的text.

Another approach is to simply have both UIImageView and UILabel/UITextView objects in the view, and if you have an image from the server, set the image of the UIImageView, and text, set the text of the UILabel/UITextView.

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