如何使用标签访问UIButton并更改其图像？

Question

我需要更改UIButtons矩阵上的图像,而我唯一知道的解决按钮的方法是标记.但我找不到一种方法来实际使用这个标识符.在viewDidLoad期间以编程方式创建按钮.

以下是创建按钮的代码:

#define N_ROWS  4
#define N_COLS  3

    int N_IMG = 0;
    for (int a = 0; a < N_COLS; a++) {
        for (int j = 0; j < N_ROWS; j++) {


            UIButton *aButton = [UIButton buttonWithType:UIButtonTypeCustom];
            aButton.frame = CGRectMake(a * 65.0 + 25, j * 65.0 + 15, 10.0, 10.0);
            aButton.tag = j + a * N_ROWS + 1;
            [aButton setBackgroundColor:[UIColor redColor]];

            N_IMG = N_IMG++;
            [self.view addSubview:aButton]; 
            number_sorted =  1;

        }
    }

以下是设置图像的代码:

- (IBAction)set_image:(id)sender {

    #define N_ROWS  4
    #define N_COLS  3

        int N_IMG = 0;
        for (int a = 0; a < N_COLS; a++) {
            for (int j = 0; j < N_ROWS; j++) {
                uibutton aButton.tag == (j + a * N_ROWS + 1) 
                setImage:[UIImage imageNamed:[puzzles objectAtIndex:N_IMG]]
                            forState:UIControlStateNormal];
            N_IMG = N_IMG++;

            }
        }
    }

这是truble开始的代码:uibutton aButton.tag ==(j + a*N_ROWS + 1)

我可以将其设置为工作吗？

Answer 1

简答:

RE:"如何使用标签访问UIButton ......"

UIButton *tmpButton = (UIButton *)[self.view viewWithTag:tmpTag];

RE:"......并改变它的形象？"

[tmpButton setImage:[UIImage imageNamed:@"MyGreatImage.png"] forState:UIControlStateNormal];

.

答案很长:

RE:*"这是truble开始的代码:uibutton aButton.tag ==(j + a*N_ROWS + 1)"*

是的,我可以看到麻烦.您使用的线路用于设置按钮的标签,而不是用于从标签获取按钮.

要从已知标记获取按钮,请执行以下操作:

// define the tag index
int tmpTag = 123;//replace "123" with your own logic, i.e. (j + a * N_ROWS + 1)

// get the button with the given tag
UIButton *tmpButton = (UIButton *)[self.view viewWithTag:tmpTag];

// assign the image
tmpImage = [UIImage imageNamed:@"MyGreatImage.png"];
[tmpButton setImage:tmpImage forState:UIControlStateNormal];

奖励代码:在此阶段,您还可以添加或删除与按钮关联的操作.

//Remove all actions associated the button
[aButton removeTarget:nil action:NULL forControlEvents:UIControlEventAllEvents];

//Assign a new button action: using the exact selector name ("myMethodName")
[aButton addTarget:self action:@selector(myMethodName:) forControlEvents:UIControlEventTouchUpInside];

//Assign a new button action: using a calculated selector name 
//(suppose I have a bunch of methods with the prefix "myNumberedMethodName_" followed by an index.
int tmpSomeNumber = 12;
SEL tmpSelector = NSSelectorFromString ([NSString stringWithFormat:@"myNumberedMethodName_%i:",tmpSomeNumber);
// don't forget to include the ":" symbol in the selector name
[aButton addTarget:self action:tmpSelector forControlEvents:UIControlEventTouchUpInside];

注意:"viewWithTag"通常返回一个View对象.Button是一种特殊类型的View,具有特殊属性,如image.因此,为了让它返回一个Button对象而不是更通用的View对象,我们通过在定义中使用(UIButton*)转换它来将其初始化为Button.

但如果您想要的只是更改按钮的不透明度,那么您不必将其作为按钮进行投射.您可以简单地将其初始化为通用视图:

// set opacity of a button
float tmpOpacity = 0.5;//half-visible
UIView *tmpView = [self.view viewWithTag:tmpTag];//get the view object associated with button's tag (remember, a button IS a view)
[[tmpView layer] setOpacity:tmpOpacity];

另请参见带标记的按钮.