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);
}];