ios - 在objective-c下将执行选择器转换为SEL

Question

UIButton我用以下代码创建了一个：

UIButton* queenButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
queenButton.frame = CGRectMake(0,50,30,30);
[queenButton setTitle:@"Q" forState:(UIControlState)UIControlStateNormal];
[queenButton addTarget:self action:(SEL)[self performSelector:@selector(promotePawnAt:to:) withObject:end withObject:@"Q"] forControlEvents:UIControlEventTouchUpInside];

当我这样做时，编译器会给出一个错误，说Cast of an Objective-C pointer to 'SEL' is disallowed with ARC. 当我移除(SEL)演员表时，我得到Implicit conversion of an Objective-C pointer to 'SEL' is disallowed with ARC.

我想要做的是让程序promotePawnAt:to:在按下按钮时调用，但是该函数需要参数，所以@selector(promotePawnAt:to:)不起作用。

Answer 1

你不能这样做。您必须创建一个带有一个参数的方法并将其添加为按钮的操作。

[queenButton addTarget:self action:@selector(action:) forControlEvents:UIControlEventTouchUpInside];

并在内部调用 yout 方法：

-(void)action:(id)button {
[self promotePawnAt:end to:@"Q"];
}