Swift 运算符“*"在两个 Int 上抛出错误

问题描述

我在这里遇到了一个非常奇怪的错误，我四处搜索并尝试了所有建议.没有工作.

scrollView.contentSize.height = 325 * globals.defaults.integer(forKey: "numCards")

二元运算符*"不能应用于两个Int"操作数

WTF 斯威夫特！为什么不?我一直乘着 Ints.这些是两个Ints.globals.defaults 只是 UserDefaults.standard 的一个实例.我每次都尝试了以下相同的错误.

325 * Int(globals.defaults.integer(forKey: "numCards")//NOPEInt(325) * Int(globals.defaults.integer(forKey: "numCards"))//NOPEif let h = globals.defaults.integer(forKey: "numCards"){325 * h//NOPE，和'条件绑定的初始化器必须具有可选类型，而不是Int'}让 h = globals.defaults.integer(forKey: "numCards") as！整数325 * h//NOPE，和'强制转换相同类型的 Int 没有影响'325 * 2//是的！但是没有狗屎...

所有这些尝试"似乎都是在浪费时间，因为我知道这两个都是Ints...我是对的.请指教.谢谢！

解决方案

该错误具有误导性.问题实际上是试图将 Int 值分配给 CGFloat 变量.

这会起作用:

scrollView.contentSize.height = CGFloat(325 * globals.defaults.integer(forKey: "numCards"))

误导性错误的原因(感谢 Daniel Hall 在下面的评论中)是由于编译器选择了返回 CGFloat 的 * 函数，因为返回需要的价值.这个相同的函数需要两个 CGFloat 参数.由于提供的两个参数是 Int 而不是 CGFloat，编译器提供了误导性错误:

二元运算符*"不能应用于两个Int"操作数

如果错误更像:

二元运算符*"不能应用于两个Int"操作数.需要两个CGFloat"操作数.

I have a very odd error here and i've searched all around and i have tried all the suggestions. None work.

scrollView.contentSize.height = 325 * globals.defaults.integer(forKey: "numCards")

WTF Swift! Why not? I multiply Ints all the time. These ARE two Ints. globals.defaults is just an instance of UserDefaults.standard. I have tried the following with the same error each time.

325 * Int(globals.defaults.integer(forKey: "numCards")   //NOPE

Int(325) * Int(globals.defaults.integer(forKey: "numCards"))  //NOPE

if let h = globals.defaults.integer(forKey: "numCards"){
    325 * h  //NOPE, and 'Initializer for conditional binding must have optional type, not Int'
}

let h = globals.defaults.integer(forKey: "numCards") as! Int
325 * h //NOPE, and 'Forced cast of Int of same type as no affect'

325 * 2 //YES!  But no shit...

All of those "attempts" seemed like a waste of time as i know for a fact both of these are Ints...and i was correct. Please advise. Thanks!

解决方案

The error is misleading. The problem is actually the attempt to assign an Int value to a CGFloat variable.

This will work:

scrollView.contentSize.height = CGFloat(325 * globals.defaults.integer(forKey: "numCards"))

The cause of the misleading error (thanks to Daniel Hall in the comments below) is due to the compiler choosing the * function that returns a CGFloat due to the return value needed. This same function expects two CGFloat parameters. Since the two arguments being provided are Int instead of CGFloat, the compiler provides the misleading error:

It would be nice if the error was more like:

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