决绝Capturing 'demo' strongly in this block is likely to lead to a retain cycle

1. - (IBAction)onTest:(id)sender
2. {
3. BlockDemo *demo = [[BlockDemo alloc]init];
4.  __weak typeof(BlockDemo) *weakDemo = demo; 
5. [demo setExecuteFinished:^{
6. if (weakDemo.resultCode == 200) {
7. NSLog(@"call back ok.");
8. }
9. }];
10. [demo executeTest];
11. }