ios - 一起点击或按下时在两个 UIlabel 之间画一条线

Question

当我用代码同时点击或按住它们时，我想在两个 UILabel 之间画一条线，我不知道该怎么做，如果有人有建议，我将不胜感激，这将是非常感谢

Answer 1

我就是这样做的。顺便说一句，我的答案经过测试......

为了管理可点击标签，我将创建自己的名为 LabelControl 的标签，它扩展了 UIControl。这个自定义控件将有一个 UILabel(为简单起见只读)作为 subview 。通过这样做，我们将能够添加 Target-Action 事件 UIControlEventTouchDown 和 UIControlEventTouchUpInside。

这是自定义标签:

.h 文件:

@interface LabelControl : UIControl
@property (nonatomic, retain, readonly) UILabel *theLabel;
@end

.m 文件:

@implementation LabelControl
@synthesize theLabel = _theLabel;

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        _theLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
        _theLabel.backgroundColor = [UIColor clearColor];
        _theLabel.userInteractionEnabled = NO;
        [self addSubview:_theLabel];
    }
    return self;
}

-(void)dealloc {

    [_theLabel release];
    [super dealloc];
}

然后对于你想画的“线”，我会使用 UIView 因为这样你就可以使用它的 hidden 属性来隐藏/显示线.在您的 ViewController 中添加此代码:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    self.label1 = [[[LabelControl alloc] initWithFrame:CGRectMake(60, 50, 200, 40)] autorelease];
    self.label1.theLabel.text = @"Hello";
    self.label1.userInteractionEnabled = YES;
    self.label1.backgroundColor = [UIColor blueColor];
    [self.label1 addTarget:self action:@selector(touchDown:) forControlEvents:UIControlEventTouchDown];
    [self.label1 addTarget:self action:@selector(touchUp:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:self.label1];

    self.label2 = [[[LabelControl alloc] initWithFrame:CGRectMake(60, 150, 200, 40)] autorelease];
    self.label2.theLabel.text = @"World";
    self.label2.userInteractionEnabled = YES;
    self.label2.backgroundColor = [UIColor purpleColor];
    [self.label2 addTarget:self action:@selector(touchDown:) forControlEvents:UIControlEventTouchDown];
    [self.label2 addTarget:self action:@selector(touchUp:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:self.label2];

    //the position of the line is hard-coded. You will have to modify this yourself
    self.theLine = [[UIView alloc] initWithFrame:CGRectMake(60, 120, 200, 3)];
    self.theLine.backgroundColor = [UIColor blueColor];
    self.theLine.hidden = YES;
    [self.view addSubview:self.theLine];
}

-(void)showOrHideLine {

    if (self.label1.selected && self.label2.selected) {
        NSLog(@"Both are selected");
        self.theLine.hidden = NO;
    } else {
        self.theLine.hidden = YES;
    }
}

-(void)touchDown:(id)sender {
    //When any of the custom label gets the touch down event set the `selected` property
    //to YES. (This property is inherited form `UIControl`
    NSLog(@"Touch down");
    LabelControl *labelControl = (LabelControl*)sender;
    labelControl.selected = YES;
    [self showOrHideLine];
}

-(void)touchUp:(id)sender {
    //When any of the custom label gets the touch up event set the `selected` property
    //to NO. (This property is inherited form `UIControl`
    NSLog(@"Touch Up");
    LabelControl *labelControl = (LabelControl*)sender;
    labelControl.selected = NO;
    [self showOrHideLine];
}

如果您有任何问题，请告诉我。希望这对您有所帮助!