为什么swift提供了CGRect初始化程序和CGRectMake函数？ [英] Why does swift provide both a CGRect initializer and a CGRectMake function?

问题描述

当我在swift中学习Core Graphics时，我在YouTube上观看的教程使用 CGRectMake 函数代替 CGRect 创建一个 CGRect 实例。

When I was learning about Core Graphics in swift, the tutorials that I watched on youtube use the CGRectMake function instead of the initializer of CGRect to create a CGRect instance.

这对我来说很奇怪。我不明白为什么我应该使用前者，因为参数是相同的，我认为使用 XXXMake 函数没有性能优势。

This is so weird to me. I don't understand why should I use the former because the parameters are the same and I think there is no performance benefit to using the XXXMake function.

此外，为什么swift甚至有一个Make函数，当 CGRect 已经有一个初始化器具有完全相同的参数？我认为模块的开发人员使用一定的设计模式，我不知道。他们使用一个吗？如果是，是什么？我真的想知道一些更多的设计模式。

Also, why does swift even have such a "Make" function, when CGRect already has an initializer with exactly the same parameters? I think the developers of the modules is using a certain design pattern that I don't know. Did they use one? If yes, what is it? I really want to know some more design patterns.

推荐答案

> CGRectMake 不是由Swift提供。

Short answer: CGRectMake is not "provided by Swift". The corresponding C function in the CoreGraphics framework is automatically imported and therefore available in Swift.

更长的答案：
在CoreGraphics
框架中的相应C函数是自动导入的，因此可在Swift中使用。 CGRectMake 是定义在
CGGeometry.h从CoreGraphics框架为

Longer answer: CGRectMake is defined in "CGGeometry.h" from the CoreGraphics framework as

CG_INLINE CGRect
CGRectMake(CGFloat x, CGFloat y, CGFloat width, CGFloat height)
{
  CGRect rect;
  rect.origin.x = x; rect.origin.y = y;
  rect.size.width = width; rect.size.height = height;
  return rect;
}

在（Objective-）C中，该函数提供了一个方便的方式
initialize a CGRect 变量：

CGRect r = CGRectMake(x, y, h, w);

Swift编译器会自动从
Foundation中导入所有函数头文件（如果它们是Swift兼容的），所以这个
导入为

The Swift compiler automatically imports all functions from the Foundation header files (if they are Swift-compatible), so this is imported as

public func CGRectMake(x: CGFloat, _ y: CGFloat, _ width: CGFloat, _ height: CGFloat) -> CGRect

您可以使用那个或Swift初始化器之一

You can either use that one, or one of the Swift initializers

public init(origin: CGPoint, size: CGSize)
public init(x: CGFloat, y: CGFloat, width: CGFloat, height: CGFloat)
public init(x: Double, y: Double, width: Double, height: Double)
public init(x: Int, y: Int, width: Int, height: Int)

我不认为它会造成任何性能差异。许多人可能会
使用 CGRectMake（），因为他们习惯了它从旧的pre swift
次。 Swift初始化程序更为快速，并且用
显式参数标签更具表现力：

I don't think that it makes any performance difference. Many people might use CGRectMake() because they are used to it from the old pre-Swift times. The Swift initializers are more "swifty" and more expressive with the explicit argument labels:

let rect = CGRect(x: x, y: x, width: w, height: h)

---

b $ b

更新：自 Swift 3 / Xcode 8 起，CGRectMake 不再是
在Swift中可用。

---

Update: As of Swift 3/Xcode 8, CGRectMake is no longer available in Swift.

这篇关于为什么swift提供了CGRect初始化程序和CGRectMake函数？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！