使用块缩短我的 Objective-C 代码

发布于 2024-09-09 21:28:12 字数 638 浏览 2 评论 0原文

这是我用来修改 UIView 的类别。该代码有效，但在第一个方法（setFrameHeight）中我使用了一个块，而在第二个方法（setFrameWidth）中我没有使用。在这个例子中，有什么方法可以更有效地使用块吗？

typedef CGRect (^modifyFrameBlock)(CGRect);

- (void) modifyFrame:(modifyFrameBlock) block {
    self.frame = block(self.frame);
}

- (void) setFrameWidth:(CGFloat)newWidth {
    modifyFrameBlock b = ^CGRect (CGRect frame) { 
        frame.size.width = newWidth;
        return frame; 
    };      
    [self modifyFrame:b];
}

- (void) setFrameHeight:(CGFloat)newHeight {
    CGRect f = self.frame;
    f.size.height = newHeight;
    self.frame = f;
}

答案可能是块不适合这么短的方法，或者其他什么。语法确实看起来很时髦。

原文

This is from a category that I'm using to modify UIView. The code works, but in the first method (setFrameHeight) I'm using a block and in the second method (setFrameWidth) I'm not. Is there any way to use blocks more efficiently in this example?

typedef CGRect (^modifyFrameBlock)(CGRect);

- (void) modifyFrame:(modifyFrameBlock) block {
    self.frame = block(self.frame);
}

- (void) setFrameWidth:(CGFloat)newWidth {
    modifyFrameBlock b = ^CGRect (CGRect frame) { 
        frame.size.width = newWidth;
        return frame; 
    };      
    [self modifyFrame:b];
}

- (void) setFrameHeight:(CGFloat)newHeight {
    CGRect f = self.frame;
    f.size.height = newHeight;
    self.frame = f;
}

The answer may be that blocks are not appropriate for such short methods, or something. The syntax sure seems funky.

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巷子口的你 2024-09-16 21:28:12

您获得的唯一好处是无需声明新矩形的局部变量，作为交换，您需要定义一个块。这并不是一件好事，尤其是因为它会分散你正在做的事情的注意力。

请注意，您的块使用可以稍微缩短：

[self modifyFrame:^(CGRect frame) {
    frame.size.width = newWidth;
    return frame; 
}];

或者甚至：

[self modifyFrame:^(CGRect* frame) {
    frame->size.width = newWidth;
}];

使用 modifyFrame: 是：

CGRect frame;
block(&frame);
self.frame = frame;

但我仍然将这种方法限制为更复杂的方法，只需要代码的一小部分不同。

The only thing you gain is not declaring the local variable for the new rect, in exchange you need to define a block. That is not a good deal, especially as it distracts from what you are doing.

Note that your block-usage could be shortened a bit:

[self modifyFrame:^(CGRect frame) {
    frame.size.width = newWidth;
    return frame; 
}];

Or even:

[self modifyFrame:^(CGRect* frame) {
    frame->size.width = newWidth;
}];

With modifyFrame: being:

CGRect frame;
block(&frame);
self.frame = frame;

But i'd still limit such approaches to more complex methods that only require minor parts of the code to be different.

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一身骄傲 2024-09-16 21:28:12

这种特殊的模式在其他情况下很有用（通常在运行时需要可扩展性的情况下），并且在 C 中经常看到用函数指针代替块（例如 qsort() 和 bsearch()< /code>。）但是，对于仅更新字段，通常的方法是从更简单的方法调用更复杂的方法：

- (void)setDisplaysUserInterface: (BOOL)flag {
    [self setDisplaysUserInterface: flag animated: YES];
}


- (void)setDisplaysUserInterface: (BOOL)flag animated: (BOOL)animated {
    [self setDisplaysUserInterface: flag animated: animated hideAfterDelay: NAN];
}

- (void)setDisplaysUserInterface: (BOOL)flag animated: (BOOL)animated hideAfterDelay: (NSTimeInterval)hideDelay {
    // and so forth
}

This particular pattern is useful in other situations (generally where extensibility is needed at runtime) and is frequently seen in C with function pointers in place of blocks (e.g. qsort() and bsearch().) For just updating a field, however, the usual way is to just call from the simpler method to the more complex one:

- (void)setDisplaysUserInterface: (BOOL)flag {
    [self setDisplaysUserInterface: flag animated: YES];
}


- (void)setDisplaysUserInterface: (BOOL)flag animated: (BOOL)animated {
    [self setDisplaysUserInterface: flag animated: animated hideAfterDelay: NAN];
}

- (void)setDisplaysUserInterface: (BOOL)flag animated: (BOOL)animated hideAfterDelay: (NSTimeInterval)hideDelay {
    // and so forth
}

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