performSelector弧警告

Question

可能重复： performSelector may cause a leak because its selector is unknown

我在非ARC中有这样的代码，它工作时没有错误或警告：

- (void)addTarget:(id)target action:(SEL)action forControlEvents:(UIControlEvents)controlEvents
{
    // Only care about value changed controlEvent
    _target = target;
    _action = action;
}

- (void)setValue:(float)value
{
    if (value > _maximumValue)
    {
        value = _maximumValue;
    } else if (value < _minimumValue){
        value = _minimumValue;
    }

    // Check range
    if (value <= _maximumValue & value >= _minimumValue)
    {
        _value = value;
        // Rotate knob to proper angle
        rotation = [self calculateAngleForValue:_value];
        // Rotate image
        thumbImageView.transform = CGAffineTransformMakeRotation(rotation);
    }
    if (continuous)
    {
        [_target performSelector:_action withObject:self]; //warning here
    }
}

但是，在我转换到project之后，我会收到以下警告：

“执行选择器可能会导致泄漏，因为其选择器是未知的。”

我想知道如何相应地修改我的代码。

Answer 1

我唯一能避免这种警告的方法就是压制它。您可以在您的构建设置中禁用它，但是我更喜欢在我知道它是假的地方使用语用来禁用它。

#       pragma clang diagnostic push
#       pragma clang diagnostic ignored "-Warc-performSelector-leaks"
            [_target performSelector:_action withObject:self];
#       pragma clang diagnostic pop

如果在几个地方都有错误，您可以定义一个宏，以便更容易地抑制警告：

#define SuppressPerformSelectorLeakWarning(Stuff) \
    do { \
        _Pragma("clang diagnostic push") \
        _Pragma("clang diagnostic ignored \"-Warc-performSelector-leaks\"") \
        Stuff; \
        _Pragma("clang diagnostic pop") \
    } while (0)

您可以使用这样的宏：

SuppressPerformSelectorLeakWarning([_target performSelector:_action withObject:self]);