Objective-C：将字符串参数传递给手势@selector

Question

我要实现的目标是：当我点击特定的UIImageView时，UITapGesture会将字符串传递到tap方法中。

我的代码如下：假设我已经有一个UIImageView对象，当我点击此图像时，它将打个电话，

UITapGestureRecognizer *tapFirstGuy = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(makeCallToThisPerson:@"1234567")];
[imageViewOne addGestureRecognizer:tapFirstGuy];

- (void)makeCallToThisPerson:(NSString *)phoneNumber
{
    NSString *phoneNum = [NSString stringWithFormat:@"tel:%@", phoneNumber];
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:phoneNum]];
}

但是，我收到以下编译错误： @selector(makeCallToThisPerson:@"1234567");

我不知道发生了什么事。为什么不能将字符串传递给private方法？

Answer 1

这是错误的，它不是有效的选择器。

    UITapGestureRecognizer *tapFirstGuy = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(makeCallToThisPerson:@"1234567")];

您需要更改为：

 UITapGestureRecognizer *tapFirstGuy = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(makeCallToThisPerson:)];

在您的方法中，参数将是tapGesture，就是这样：

 - (void)makeCallToThisPerson:(UITapGestureRecognizer *)tapGesture

您可以做几件事，以便输入一个参数：

1.-使用imageView的标签，tapGesture知道该视图比它所附的视图，您可以使用标签视图：

 UITapGestureRecognizer *tapFirstGuy = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(makeCallToThisPerson:)];
         imageViewOne.tag = 1234567
        [imageViewOne addGestureRecognizer:tapFirstGuy];

- (void)makeCallToThisPerson:(UITapGestureRecognizer *)tapGesture
 {
NSString *phoneNum = [NSString stringWithFormat:@"tel:%ld",tapGesture.view.tag];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:phoneNum]];
 }

其他选项，子类化是为了将NSString附加到imageView作为新属性。

Answer 2

您可以尝试编写如下子类的另一种方法UITapGestureRecognizer：-

@interface customTapGestureRecognizer : UITapGestureRecognizer

@property (nonatomic, strong) NSString * phoneNumber;

@end


// customTapGestureRecognizer.m

@implementation customTapGestureRecognizer

@end


// =====================

....

customTapGestureRecognizer *singleTap = [[customTapGestureRecognizer alloc] initWithTarget:self action:@selector(makeCallToThisPerson:)];

singleTap.phoneNumber = @"1234567";


-(void) makeCallToThisPerson:(UITapGestureRecognizer *)tapRecognizer {

customTapGestureRecognizer *tap = (customTapGestureRecognizer *)tapRecognizer;

NSLog(@"phoneNumber : %@", tap.phoneNumber);

}

注意： - 编写子类的优点是您可以在UITapGestureRecognizer.