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
