Ios UIScrollview在设置ContentSize后不滚动

我以编程方式创建了一个UIScrollView，它不会滚动：

CGRect prevFrame;
        BOOL isFirst = TRUE;
        UIScrollView *view_scroll = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
        view_scroll.contentSize = CGSizeMake(650,224*[_cases count]+25*[_cases count]);
        view_scroll.showsVerticalScrollIndicator = YES;
        view_scroll.scrollEnabled = YES;
        NSLog(@"%f",view_scroll.contentSize.height);
        [self.view addSubview:view_scroll];
        for(SLSCase* patientCase in _cases){
            SLSCaseCard* caseCard  = [[[NSBundle mainBundle] loadNibNamed:@"SLSCaseCard" owner:self options:nil] objectAtIndex:0];
            if(isFirst){
                caseCard.frame = CGRectMake(25,25, caseCard.frame.size.width, caseCard.frame.size.height);
                isFirst = FALSE;
            }
            else{
                caseCard.frame = CGRectMake(25, prevFrame.origin.y+caseCard.frame.size.height+25, caseCard.frame.size.width, caseCard.frame.size.height);
            }
            prevFrame = caseCard.frame;
            [view_scroll addSubview:caseCard];
        }

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如您所见，我已设置contentSize和scrollEnabled。它仍然没有滚动

由于自动布局中的scrollView功能，contentSize正在重新定义。要解决此问题，可以在viewDidLayoutSubviews中禁用自动布局或设置内容大小

-(void)viewWillLayoutSubviews {
    [super viewDidLayoutSubviews];
    view_scroll.contentSize = CGSizeMake(650,224*[_cases count]+25*[_cases count]);
}

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您的内容大小可能小于您的scrollview框架。您确定在_案例中有项目吗？您能在屏幕上看到内容位于屏幕底部下方吗？请先尝试将大小分配给CGSize变量，然后检查值以确保大小正确