JSJP_Student/jiaPei/Category/UIViewController/UIViewController+ModalPresentationStyle.m

//
//  UIViewController+ModalPresentationStyle.m
//  jiaPei
//
//  Created by 张嵘 on 2020/3/14.
//  Copyright © 2020 JCZ. All rights reserved.
//

#import "UIViewController+ModalPresentationStyle.h"
#import <objc/runtime.h>


@implementation UIViewController (ModalPresentationStyle)
+ (void)load {
    // 方法交换，为的是当系统调用viewDidLoad时候，调用的是我们的my_viewDidLoad方法
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [self class];
        SEL originalSelector = @selector(viewDidLoad);
        SEL swizzledSelector = @selector(my_viewDidLoad);
        Method originalMethod = class_getInstanceMethod(class, originalSelector);
        Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
        BOOL success = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
        if (success) {
            class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod);
        }
    });
}
 
- (void)my_viewDidLoad {
    
    [self my_viewDidLoad]; // 由于方法交换，实际上调用的是系统的viewDidLoad
    
    NSArray *viewcontrollers=self.navigationController.viewControllers;
    if (viewcontrollers.count > 1) {
        
    } else {
        //present方式
        self.modalPresentationStyle = UIModalPresentationFullScreen;  // 修改默认值
    }
}
@end