用于回调的 iOS NSError/NSDictionary

Question

我正在开发一个需要错误回调的框架。我使用委托方法向框架的用户（开发人员）提供错误回调。我可以使用 NSError 来指示委托方法中的错误详细信息，还是直接使用 NSDictionary 来代替？这里是否存在内存问题？

Answer 1

您应该使用具有适当错误处理的块来代替委托方法，如下所示：

界面：

typedef void(^ResultBlock)(id result, NSError *error);

extern NSString * const DummyErrorDomain;

enum{
    DummyErrorReason1,
    DummyErrorReason2
};

@interface Dummy : NSObject

-(void)doSomething:(ResultBlock)resultBlock;

@end

使用异步 NSURLConnection 实现：

NSString * const DummyErrorDomain = @"DummyErrorDomain";

@interface Dummy ()

@property (strong) ResultBlock resultBlock;
@property NSURLConnection *connection;
@property NSMutableData *responseData;

@end

@implementation Dummy

-(void)doSomething:(ResultBlock)resultBlock
{
    self.resultBlock = resultBlock;
    self.responseData = [[NSMutableData alloc] init];

    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:@"dummyURL"]];

     self.connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
}

-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
    self.resultBlock(nil,error);
}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection{
    self.resultBlock(self.responseData, nil);
}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    [self.responseData appendData:data];
}

@end

用法：

-(void)usage
{
    Dummy *dummy = [[Dummy alloc] init];

    [dummy doSomething:^(id result, NSError *error) {
        if(result){
            // everything went fine
        }else{
            // error handling
        }
    }];
}