从iPhone上的其他两个UIImages创建一个UIImage [英] Create a UIImage from two other UIImages on the iPhone

问题描述

我正试图在iPhone上写一个动画，没有太大成功，崩溃似乎没什么用。

I'm trying to write an animation on the iPhone, without much success, getting crashes and nothing seems to work.

我想做的事情看似简单，创造一个UIImage，并将另一个UIImage的一部分绘制到其中，我对上下文和图层和东西有点混淆。

What I wanna do appears simple, create a UIImage, and draw part of another UIImage into it, I got a bit confused with the context and layers and stuff.

有人可以解释如何写这样的东西（有效地），带有示例代码？

Could someone please explain how to write something like that (efficiently), with example code?

推荐答案

为了记录，事实证明这是相当简单的 - 你需要知道的一切在下面的示例中的某处：

For the record, this turns out to be fairly straightforward - everything you need to know is somewhere in the example below:

+ (UIImage*) addStarToThumb:(UIImage*)thumb
{
   CGSize size = CGSizeMake(50, 50);
   UIGraphicsBeginImageContext(size);

   CGPoint thumbPoint = CGPointMake(0, 25 - thumb.size.height / 2);
   [thumb drawAtPoint:thumbPoint];

   UIImage* starred = [UIImage imageNamed:@"starred.png"];

   CGPoint starredPoint = CGPointMake(0, 0);
   [starred drawAtPoint:starredPoint];

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

   return result;
}

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