动态设置内联 UIViewController 指针 - Objective C

Question

我有一个带有 for 循环的 iOS 应用程序，可以创建、设置自定义视图控制器并将其添加到我的视图中。问题是我需要根据当前循环数将 UIViewController 对象动态设置为正确的 class。这是我的代码：

// Loop through the data and setup the switches.
    
for (NSUInteger loop = 0; loop < [switchLabels count]; loop++) {
        
    // Create the view controller object.
    UIViewController *screen;
        
    // Create the custom switch view.
        
    if (loop < 3) {
        screen = [[CustomSwitchView alloc] initWithNibName:@"CustomSwitchView" bundle:nil];
    } else {
        screen = [[CustomTripleSwitchView alloc] initWithNibName:@"CustomTripleSwitchView" bundle:nil];
    }
        
    // Create the custom switch view.
    [screen setPassedInType:switchTypes[loop]];
    [screen setDelegate:self];
    [self addChildViewController:screen];
    [screen.view setFrame:CGRectMake((self.view.frame.size.width - 150), ((UILabel *)switchLabels[loop]).frame.origin.y, 144, 72)];
    [scrollTopView addSubview:screen.view];
    [screen didMoveToParentViewController:self];
    [screen setTitles:switchTitles[loop] state:[switchSettings[loop] boolValue]];
}

问题是上面的一些方法调用出现了错误：

No visible @interface for 'UIViewController' declares the selector....

为了解决这个问题，我需要对对象进行类型转换screen。但是，我需要根据 for 循环编号对其进行动态类型转换：

如果循环小于3，我需要将对象类型转换为CustomSwitchView，否则我需要将其类型转换为CustomTripleSwitchView。我怎样才能做到这一点？例如，我尝试了下面的代码，但没有成功：

(loop < 3 ? (CustomSwitchView *) : (CustomTripleSwitchView *))

Answer 1

有几种方法可以解决这个问题。对现有代码影响最小的是将方法区分为一般适用于 UIViewController 的方法和特定于 subclasses 的方法。对声明为特定 subclass...

的堆栈变量调用 subclass 方法

for (NSUInteger loop = 0; loop < [switchLabels count]; loop++) {

    // Create the view controller object.
    UIViewController *vc;

    // Create the custom switch view.

    if (loop < 3) {
        CustomSwitchView *screen = [[CustomSwitchView alloc] initWithNibName:@"CustomSwitchView" bundle:nil];
        [screen setPassedInType:switchTypes[loop]];
        [screen setDelegate:self];
        [screen setTitles:switchTitles[loop] state:[switchSettings[loop] boolValue]];
        vc = screen;
    } else {
        CustomTripleSwitchView *screen = [[CustomTripleSwitchView alloc] initWithNibName:@"CustomTripleSwitchView" bundle:nil];
        [screen setPassedInType:switchTypes[loop]];
        [screen setDelegate:self];
        [screen setTitles:switchTitles[loop] state:[switchSettings[loop] boolValue]];
        vc = screen;
    }

    // Create the custom switch view.
    [self addChildViewController:vc];
    [vc.view setFrame:CGRectMake((self.view.frame.size.width - 150), ((UILabel *)switchLabels[loop]).frame.origin.y, 144, 72)];
    [scrollTopView addSubview:vc.view];
    [vc didMoveToParentViewController:self];
}

如果我们在项目中遇到此问题，这是一个不错的解决方案。当你看到这种事情激增时，是时候开始思考了：(a) 我应该为每个 class 定义一个协议（正如评论者恰当地建议的那样），或者 (b) 这些真的是 subclass 彼此相关，例如 CustomTripleSwitchView 实际上是 CustomSwitchView 的子 class?

动态设置内联 UIViewController 指针 - Objective C

Dynamically set UIViewController pointer inline - Objective C

cocoa-touch

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objective-c

uiviewcontroller

ios