block 方法参数中带有block 如何生成 如何使用

typedef void(^SDWebImageDownloaderProgressBlock)(NSInteger receivedSize, NSInteger expectedSize);
@interface ssyTest : NSObject
{
    SDWebImageDownloaderProgressBlock ssyblock;
}
- (void)testssy:(NSString *)str block:(SDWebImageDownloaderProgressBlock)ssy;

#import "ssyTest.h"

@implementation ssyTest
- (void)testssy:(NSString *)str block:(SDWebImageDownloaderProgressBlock)ssy
{
    ssyblock = ssy;
    [self performSelector:@selector(jjj) withObject:nil afterDelay:5];
}

- (void)jjj
{
    ssyblock(1,2);
}

    ssyTest *ssy = [[ssyTest alloc] init];
    [ssy testssy:@"3" block:^(NSInteger s1,NSInteger s2){
        
        
        NSLog(@"%d   %d",s1,s2);
    }];

- (void)testCallback:(void (^)(int ssy,NSString *str))callback;

- (void)testCallback:(void (^)(int ssy,NSString *str))callback
{
    callback(5,@"ssy");
}

  [ssy testCallback:^(int index,NSString *str){
        NSLog(@"%d   %@",index,str);
    }];