let loadingGroup = let loadingGroup = STLoadingGroup(side: side, style: style)
loadingGroup.show(inView: view)
loadingGroup.startLoading()
// stop:  loadnigGroup.stopLoading()

protocol STLoadingable {
    var isLoading: Bool { get }
    
    func startLoading()
    func stopLoading()
}

protocol STLoadingConfig {
    var animationDuration: TimeInterval { get }
    var lineWidth: CGFloat { get }
    var loadingTintColor: UIColor { get }
}

enum STLoadingStyle: String {
    case submit = "submit"
    case glasses = "glasses"
    case walk = "walk"
    case arch = "arch"
    case bouncyPreloader = "bouncyPreloader"
    case zhihu = "zhihu"
    case triangle = "triangle"
    case pacMan = "pac man"
}

class STLoadingGroup {
    fileprivate let loadingView: STLoadingable
    
    init(side: CGFloat, style: STLoadingStyle) {
        
        let bounds = CGRect(origin: .zero, size: CGSize(width: side, height: side))
        switch style {
        case .submit:
            loadingView = STSubmitLoading(frame: bounds)
        case .glasses:
            loadingView = STGlassesLoading(frame: bounds)
        case .walk:
            loadingView = STWalkLoading(frame: bounds)
        case .arch:
            loadingView = STArchLoading(frame: bounds)
        case .bouncyPreloader:
            loadingView = STBouncyPreloaderLoading(frame: bounds)
        case .zhihu:
            loadingView = STZhiHuLoading(frame: bounds)
        case .triangle:
            loadingView = STTriangleLoading(frame: bounds)
        case .pacMan:
            loadingView = STPacManLoading(frame: bounds)
        // insert your code here
        }
    }
}