ios - 如何在 IOS 中将回调方法作为参数传递

Question

我将根据下面的例子解释需求

这是异步操作后需要调用的方法

    -(void) myCallbackMethodOne: (NSString *)response
    {
        //method to be called
    }

    -(void) myCallbackMethodTwo: (NSString *)response
    {
        //method to be called
    }



    -(void) getDataFromServerWithCallback: (NSString *)requestString _Callback(CallbackMethod *) methodName
    {
        //logic to send request and 
        //to set callback method something similar to
        [setCallbackMethod  methodName]; 
    }

    -(void) onDataRecievedFromServerWithResponse: (NSString *) response //this method gets called as part of framework
    {
        [callTheCallbackMethod: response]; 
    }

调用方法来演示需求的地方

    -int main()
    {
        [getDataFromFromServerWithCallback: @"getTopNews" _Callback:myCallbackMethodOne];  //this is the requirement; I should be able to pass myCallbackMethod as argument

        [getDataFromFromServerWithCallback: @"getBusinessNews" _Callback:myCallbackMethodTwo];  //this is the requirement; I should be able to pass myCallbackMethod as argument

    }

Answer 1

此类功能有两种成熟的模式:

1) 委托(delegate):

@protocol ResponseDelegate
- (void)handleResponse:(NSString *)response;
@end

@interface CommsClass : NSObject
@property (weak) id<ResponseDelegate> delegate;
- (void)sendRequest:(NSString *)request;
@end

@interface CallingClass : NSObject <ResponseDelegate>
{
    CommsClass _commsClass;
}

- (void)callingCode;
@end

@interface CallingCode

- (void)callingCode
{
    _commsClass = [CommsClass new];
    _commsClass.delegate = self;
    [_commsClass sendRequest:@"Blah"];
}

- (void)handleResponse:(NSString *)response
{
    NSLog(@"Whoot: %@", response);
}

@end

2) block 。

typedef (^HandleResponseBlock)(NSString *response);

@interface CommsClass : NSObject
- (void)sendRequest:(NSString *)request
withCompletionBlock:(HandleResponseBlock)block;
@end