Question

我使用for循环在滚动条上创建多个图像和滑块，如何通过更改滑块的值来更改图像的alpha？这是我的代码我试图在函数loadImages之外声明uiimages，但我不认为这是个好主意。我知道如何在不使用for循环的情况下完成它，但是如果我想使用for循环，我怎么能让函数知道它应该在哪个uiimage上运行。因为在for循环中创建的所有uiimages都不是我认为的公共对象。

-(void)loadImages
{

for (int i = 0; i < 10; i++){
    //show drawing position in the output
    NSLog(@"x:%i, y:%i",xInc, yInc);
    //text label on the slider button
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(78 + xInc, 55+yInc, 200, 20)];
    Person *thisPerson = [arrayOfPerson objectAtIndex:i];
    NSString *namePerson = thisPerson.name;
    [label setText:[NSString stringWithFormat:@"%@",namePerson]];
    [label setTextColor:[UIColor whiteColor]];
    [label setBackgroundColor:[UIColor clearColor]];
    label.textAlignment = NSTextAlignmentCenter;
    //front office background image of slider
    NSString *frontimageName = [NSString stringWithFormat:@"frontofficeBUTTON.png"];
    UIImageView *frontimgView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:frontimageName]];
    frontimgView.frame = CGRectMake(xInc, 10 + yInc, 332, 70);
    [frontimgView setTag:i];
    //back office background image of slider
    NSString *backimageName = [NSString stringWithFormat:@"backofficeBUTTON.png"];
    UIImageView *backimgView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:backimageName]];
    backimgView.frame = CGRectMake(xInc, 10 + yInc, 332, 70);
    [backimgView setTag:i];
    //slider
    UISlider *slider=[[UISlider alloc] initWithFrame:CGRectMake(5+ xInc, 25+yInc, 322, 40)];
    //give a id tag to the slider
    [slider setTag:i];
    //set a action to the slider
    [slider addTarget:self action:@selector(UnlocklinkSlider:) forControlEvents:UIControlEventTouchUpInside];
    //define the appearance of the slider
    UIImage *stetchLeftTrack= [[UIImage imageNamed:@"Nothing.png"]
                               stretchableImageWithLeftCapWidth:30.0 topCapHeight:0.0];
    UIImage *stetchRightTrack= [[UIImage imageNamed:@"Nothing.png"]
                                stretchableImageWithLeftCapWidth:30.0 topCapHeight:0.0];
    [slider setThumbImage: [UIImage imageNamed:@"rightBUTTON.png"] forState:UIControlStateNormal];
    [slider setMinimumTrackImage:stetchLeftTrack forState:UIControlStateNormal];
    [slider setMaximumTrackImage:stetchRightTrack forState:UIControlStateNormal];
    yInc = yInc + 80;
    [_scrollView addSubview:backimgView];
    [_scrollView addSubview:frontimgView];
    [_scrollView addSubview:label];
    [_scrollView addSubview:slider];
}
[_scrollView setContentSize:CGSizeMake(320, scrollLength)];
}

- (void)UnlocklinkSlider:(UISlider*)slider 
{...}

Answer 1

您的滑块应为UIControlEventValueChanged添加目标和操作，以便图像同步更新（尽管它也会在触摸时起作用）。获得回调时，使用滑块标签查找带有匹配标记的图像视图。然后将图片视图alpha设置为slider.value。

要查找图像视图，您可以循环滚动视图的子视图并检查子视图的标记。您需要更改当前代码中的标记，因为您有许多具有相同标记的内容。

更好的选择是在控制器的数组属性中存储对图像视图的引用，然后使用滑块标记作为该数组中的索引。

Objective-C：我如何改变for循环创建的uiimages的alpha

1 个答案: