performSelector may cause a leak because its selector is unknown IN Singleton Class/ FUNCTION Pointer -Passing Function as parameter

Question

@interface URLClass : NSObject
{
    id target;
    SEL funObj;
}
+ (URLClass *)sharedInstance;
-(void)theBigFunction:(SEL)func :(id)target;
@property (nonatomic,retain) SEL funObj;

#import "URLClass.h"

static URLClass *instance = NULL;


@implementation URLClass
{
    NSMutableData *webData;
}
- (id)init
{
    if ( self = [super init] )
    {

    }
    return self;    
}

+ (URLClass *)sharedInstance
{
    @synchronized([URLClass class])
    {
        if (!instance)
            instance = [[super alloc] init];        
        return instance;
    }    
    return nil;
}
-(void)theBigFunction:(SEL)func :(id)targetObj{

    funObj =func;
    target=targetObj;  
    NSURL *URL = [NSURL URLWithString:@"urlString"];    
    NSURLRequest *request = [NSURLRequest requestWithURL:URL];
    NSURLConnection *connection = [NSURLConnection connectionWithRequest:request delegate:self];

    if( connection )
    {
        webData = [NSMutableData data] ;
    }
    else
    {
        NSLog(@"theConnection is NULL");
    }
}



-(BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace
{

    return YES;
}
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [webData setLength: 0];
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    [webData appendData:data];
}
-(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{    
    NSLog(@"ERROR with theConenction");
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{    

    NSError *error;
    id jsonObj = [NSJSONSerialization JSONObjectWithData:webData options:0 error:&error];    
    if (jsonObj!=nil && error==nil) {        
        if ([jsonObj isKindOfClass:[NSDictionary class]]) {            
            NSDictionary *dic=(NSDictionary*)jsonObj;
            NSLog(@"DIC jsonObj %@ ",dic);
            NSArray *array=[dic objectForKey:@"items"];
            NSLog(@"array jsonObj %@  %d",array,[array count]);
        }else if ([jsonObj isKindOfClass:[NSArray class]]) {

            NSArray *arr=(NSArray*)jsonObj;
            NSLog(@"arr jsonObj %@ ",arr);
        }
    }
    [target performSelector:funObj];
// Not gEtting called the aboue line

//performSelector may cause a leak because its selector is unknown warning in above line }

When am planing to execute below lines form code from any class . its not get called.

-(void)loginPress:(id)sender{
    URLClass *rlOBJ=[URLClass sharedInstance];   
    [rlOBJ theBigFunction:@selector(upd_Handler:) :self];
}
- (void) upd_Handler: (id) value{

    NSLog( @"Seccess");    
}

Answer 1

The modern approach would be for your class to accept a completion block instead of a target / selector. Then you don’t have to insert a bunch of ugly compiler-inhibiting lines, and you get more flexibility.