iOS:如何将 UIViewAnimationCurve 转换为 UIViewAnimationOptions? [英] iOS: How to convert UIViewAnimationCurve to UIViewAnimationOptions?

问题描述

UIKeyboardAnimationCurveUserInfoKey 有一个 UIViewAnimationCurve 值.如何将其转换为相应的 UIViewAnimationOptions 值以与 +[UIView animateWithDuration:delay:options:animations:completion:]options 参数一起使用代码>?

The UIKeyboardAnimationCurveUserInfoKey has a UIViewAnimationCurve value. How do I convert it to the corresponding UIViewAnimationOptions value for use with the options argument of +[UIView animateWithDuration:delay:options:animations:completion:]?

// UIView.h

typedef enum {
    UIViewAnimationCurveEaseInOut,         // slow at beginning and end
    UIViewAnimationCurveEaseIn,            // slow at beginning
    UIViewAnimationCurveEaseOut,           // slow at end
    UIViewAnimationCurveLinear
} UIViewAnimationCurve;

// ...

enum {
    // ...
    UIViewAnimationOptionCurveEaseInOut            = 0 << 16, // default
    UIViewAnimationOptionCurveEaseIn               = 1 << 16,
    UIViewAnimationOptionCurveEaseOut              = 2 << 16,
    UIViewAnimationOptionCurveLinear               = 3 << 16,
    // ...
};
typedef NSUInteger UIViewAnimationOptions;

显然，我可以使用 switch 语句创建一个简单的类别方法，如下所示:

Obviously, I could create a simple category method with a switch statement, like so:

// UIView+AnimationOptionsWithCurve.h

@interface UIView (AnimationOptionsWithCurve)
@end

// UIView+AnimationOptionsWithCurve.m

@implementation UIView (AnimationOptionsWithCurve)

+ (UIViewAnimationOptions)animationOptionsWithCurve:(UIViewAnimationCurve)curve {
    switch (curve) {
        case UIViewAnimationCurveEaseInOut:
            return UIViewAnimationOptionCurveEaseInOut;
        case UIViewAnimationCurveEaseIn:
            return UIViewAnimationOptionCurveEaseIn;
        case UIViewAnimationCurveEaseOut:
            return UIViewAnimationOptionCurveEaseOut;
        case UIViewAnimationCurveLinear:
            return UIViewAnimationOptionCurveLinear;
    }
}

@end

但是，有没有更简单/更好的方法?

But, is there an even easier/better way?

推荐答案

可以说，您可以采用第一个解决方案并将其设为内联函数，以节省堆栈推送.这是一个非常严格的条件(常量绑定等)，它应该编译成一个非常小的程序集.

Arguably you can take your first solution and make it an inline function to save yourself the stack push. It's such a tight conditional (constant-bound, etc) that it should compile into a pretty tiny piece of assembly.

根据@matt，你开始吧(目标-C):

Per @matt, here you go (Objective-C):

static inline UIViewAnimationOptions animationOptionsWithCurve(UIViewAnimationCurve curve)
{
  switch (curve) {
    case UIViewAnimationCurveEaseInOut:
        return UIViewAnimationOptionCurveEaseInOut;
    case UIViewAnimationCurveEaseIn:
        return UIViewAnimationOptionCurveEaseIn;
    case UIViewAnimationCurveEaseOut:
        return UIViewAnimationOptionCurveEaseOut;
    case UIViewAnimationCurveLinear:
        return UIViewAnimationOptionCurveLinear;
  }
}

斯威夫特 3:

extension UIViewAnimationOptions {
    init(curve: UIViewAnimationCurve) {
        switch curve {
            case .easeIn:
                self = .curveEaseIn
            case .easeOut:
                self = .curveEaseOut
            case .easeInOut:
                self = .curveEaseInOut
            case .linear:
                self = .curveLinear
        }
    }
}

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