在objective-c中创建自定义动态类

在我的应用程序中,我有一个UIViewController,我使用了很多UIAlertView向用户提问.

因为我需要每个UIAlertView的响应我已经使我的控制器成为UIAlertViewDelegate的委托,这工作正常,但在7 UIAlertView之后,我试图找到一种更好的方式来使用委托.

在java中,我知道我可以为单个目的创建内联类,例如在这个问题中：Java – inline class definition

我想知道的是：有没有办法创建一个动态委托的类？实现这样的目标

id<UIAlertViewDelegate> myCustomClass = @class {
    my class code goes here
}

UIAlertView* alertView;
alertView = [[UIAlertView alloc] initWithTitle:@"Title"
                                       message:@"Message"
                                      delegate:myCustomClass
                             cancelButtonTitle:@"No"
                             otherButtonTitles:@"OK",@"Sure",@"Maybe",nil] ];    
[alertView show];

解决方法

不 – Objective-C中没有“内联类”.话虽如此,您可以使用objective-c在运行时创建自定义对象,这有点涉及,但我愿意分享一些代码来做你所说的.

这是一个例子：

NSObject Subclass.h

#import <objc/runtime.h>

typedef struct selBlockPair { SEL aSEL; id (^__unsafe_unretained aBlock)(id,...); } selBlockPair;
#define NIL_PAIR ((struct selBlockPair) { 0,0 })
#define PAIR_LIST (struct selBlockPair [])
#define BLOCK_CAST (id (^)(id,...))

@interface NSObject (subclass)

+(Class) newSubclassNamed:(Nsstring *) name
            protocols:(Protocol **) protos
                 impls:(selBlockPair *) impls;

@end

NSObject Subclass.m

@implementation NSObject (subclass)

+(Class) newSubclassNamed:(Nsstring *)name
             protocols:(Protocol **)protos
                 impls:(selBlockPair *)impls
{
    if (name == nil)
    {
        // basically create a random name
        name = [Nsstring stringWithFormat:@"%s_%i_%i",class_getName(self),arc4random(),arc4random()];
    }

    // allocated a new class as a subclass of self (so I Could use this on a NSArray if I wanted)
    Class newClass = objc_allocateClasspair(self,[name UTF8String],0);

    // add all of the protocols untill we hit null
    while (protos && *protos != NULL)
    {
        class_addProtocol(newClass,*protos);
        protos++;
    }

    // add all the impls till we hit null
    while (impls && impls->aSEL)
    {
        class_addMethod(newClass,impls->aSEL,imp_implementationWithBlock(impls->aBlock),"@@:*");
        impls++;
    }

    // register our class pair
    objc_registerClasspair(newClass);

    return newClass;
}

@end

用法示例：

int main()
{
    @autoreleasepool {
        __strong Class newClass = [Nsstring newSubclassNamed:@"MyCustomString" protocols:NULL impls: PAIR_LIST {
            @selector(description),BLOCK_CAST ^id (id self) {
                return @"testing";
            },NIL_PAIR
        }];

        Nsstring *someString = [newClass new];
        NSLog(@"%@",someString);
    }
}

输出：

2012-10-01 10:07:33.609 TestProj[54428:303] testing