深拷贝一个UILabel

原理还是用到runtime的反射机制和NSCopying协议.

extension UILabel:NSCopying
{
    public func copy(with zone: NSZone? = nil) -> Any {
        
        let label = UILabel()
        
        var outCount:UInt32
        
        var propertyArray:[NSString] = [NSString]()
        
        outCount = 0
        
        let peopers:UnsafeMutablePointer<objc_property_t?>! =  class_copyPropertyList(UILabel.classForCoder(),&outCount)
        
        let count:Int = Int(outCount);
        
        for i in 0...(count - 1)
        {
            let method = peopers[i]
            
            let sel = method_getName(method)
            
            let methodName = sel_getName(sel)
            
            if let name = methodName
            {
                let na:NSString = NSString.init(utf8String: name)!
                
                propertyArray.append(na);
            }
        }
        
        // 不要忘记释放内存，否则C语言的指针很容易成野指针的
        free(peopers)
        
        for i in 8...(count - 6)
        {
            let name  = propertyArray[i]
            let value = self.value(forKey: name as String)
            label.setValue(value,forKey: name as String)
        }
        
        return label
    }
}

let labelA = UILabel()

let labelB =  labelA.copy() as! UILabel