1.获取当前viewController

-(UIViewController *)viewController{
    
    UIResponder *next = [self nextResponder];
    do {
        if ([next isKindOfClass:[UIViewController class]]) {
            
            return (UIViewController*)next;
        }
        next = [next nextResponder];
        
    } while (next!= nil);
    
    return nil;
}

2.NSURL URLWithString return nil 问题解决

1 已经弃用的方法

// 经过转义的URL
NSString* webStringURL = [routeString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSURL *routeURL = [NSURL URLWithString:webStringURL];

2.iOS9之后的方法

NSString *str1 =[str stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
NSURL *routeURL = [NSURL URLWithString:str1];

https://www.jianshu.com/p/dbb15f019127
https://www.jianshu.com/p/dbb15f019127

3.iOS 9不能访问HTTP的解决方法（链接、图片链接、视频链接）

在Xcode工程中找到Info.plist文件，添加

image.png

4.