iOS表达式结果未在viewDidLoad方法中使用

Question

I'm working on an iOS app and need to display a PickerView containing two components, one with strings and one with UIImageViews. In the view controller's class extension, I've created a NSArray called "suites" to hold the UIImages, and populate the array in the viewDidLoad method:

viewDidLoad method

I've also assigned the view controller to be the PickerView's delegate and data source. I have to global variables to identify PickerView's two components:

#define numberComponent 0
#define suiteComponent 1

and have implemented the following delegate method:

- (UIView *)pickerView:(UIPickerView *)pickerView
            viewForRow:(NSInteger)row
            forComponent:(NSInteger)component
            reusingView:(nullable UIView *)view
{
    if (component == suiteComponent){
        UIImageView *imageView = (UIImageView *) view;
        if(!imageView){
            imageView = [[UIImageView alloc] initWithImage: self.suites[row]];
        }
        imageView.image = self.suites[row];
        return imageView;
    }
    else{
        UILabel *label = (UILabel *) view;
        if(!label){
            label = [[UILabel alloc] init];
        }
        label.text = self.numbers[row];
        return label;
    }
}

In the simulator, the picker component containing the UILabels is rendering just fine. The component containing the UIImageViews will not show up, and I am guessing it is because the array of UIImages is not being used:

simulator

Update: The block within if(component == suiteComponent) is never reached. I have this datasource method:

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 2;
}

so if my understanding is correct, UIPickerView should eventually make a call to its delegate to render the second component. However when I debug it, the delegate method's row parameter stays between 0 and 4 throughout all of the calls, and the component variable stays at 0.

I'd appreciate any help, thank you!

Answer 1

That is incorrect way to initiate a custom object.

You should do it like this:

self.suites = [[Suites alloc] initWithObjects:@[heart,club,spade,diamond]];

then u can use self.suites properly. Note I assumed your custom object class name is "Suites". You need to change that name to whatever your custom class name is. I also assume the function accepts NSArray, thus I create the literal ObjC array @[..].

And the parameters passing is suspicious too. You don't need to cast the object types in parameters passing. You need to check the custom class's initWithObjects: declaration. Is it declared to input arrays or UIImage?