headerViewForSection：如果 Header View 或 section 在 iphone 上不可见，则返回 nil
Posted
技术标签:
【中文标题】headerViewForSection：如果 Header View 或 section 在 iphone 上不可见，则返回 nil【英文标题】：headerViewForSection: returns nil if Header View or section is not visible on the iphone 【发布时间】：2015-02-03 10:59:27 【问题描述】：我正在使用我添加到标题视图的 UIButton 检查 numberOfRowsInSection: 方法，并在按钮状态上检查该部分中是否存在行。但是当我的应用程序崩溃时 [self.tableView headerViewForSection:section] 返回 nil。由于它对于可见的部分工作正常，我假设这是因为我的部分目前不可见。
这是我创建节标题视图的方法：
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
UITableViewHeaderFooterView *myHeader = [tableView dequeueReusableHeaderFooterViewWithIdentifier:HeaderIdentifier];;
if(!myHeader)
myHeader = [[UITableViewHeaderFooterView alloc] initWithReuseIdentifier:HeaderIdentifier];
UIView *sectionHeaderView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
sectionHeaderView.tag = 1001;
sectionHeaderView.backgroundColor = [UIColor whiteColor];
NSDictionary *sectionDict = [self.sectionArray objectAtIndex:section];
NSString *sectionName = [sectionDict objectForKey:@"name"];
if ([sectionName isEqualToString:@"Verified Seller"])
UIImageView *sectionHeaderImageView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 0, 44, 44)];
sectionHeaderImageView.image = [UIImage imageNamed:@"blue_ok.png"];
[sectionHeaderImageView setContentMode:UIViewContentModeCenter];
[sectionHeaderView addSubview:sectionHeaderImageView];
UILabel *sectionHeaderLabel = [[UILabel alloc] initWithFrame:CGRectMake(74, 5, 200, 34)];
sectionHeaderLabel.textColor = [UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1];
sectionHeaderLabel.font = [UIFont fontWithName:@"Avenir-Medium" size:16];
sectionHeaderLabel.text = @"Verified Seller";
[sectionHeaderView addSubview:sectionHeaderLabel];
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(15, 43, 305, 1)];
view.backgroundColor = [UIColor colorWithRed:217.0f/255.0f green:217.0f/255.0f blue:217.0f/255.0f alpha:1];
[sectionHeaderView addSubview:view];
else if ([sectionName isEqualToString:@"Pro-Seller"])
UIImageView *sectionHeaderImageView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 0, 44, 44)];
sectionHeaderImageView.image = [UIImage imageNamed:@"blue_ok.png"];
[sectionHeaderImageView setContentMode:UIViewContentModeCenter];
[sectionHeaderView addSubview:sectionHeaderImageView];
UILabel *sectionHeaderLabel = [[UILabel alloc] initWithFrame:CGRectMake(74, 5, 200, 34)];
sectionHeaderLabel.textColor = [UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1];
sectionHeaderLabel.font = [UIFont fontWithName:@"Avenir-Medium" size:16];
sectionHeaderLabel.text = @"Pro Seller";
[sectionHeaderView addSubview:sectionHeaderLabel];
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(15, 43, 305, 1)];
view.backgroundColor = [UIColor colorWithRed:217.0f/255.0f green:217.0f/255.0f blue:217.0f/255.0f alpha:1];
[sectionHeaderView addSubview:view];
else if ([sectionName isEqualToString:@"Diagnostic"])
UIButton *diagnosticBtn = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
[diagnosticBtn setTitle:@"Diagnostic Report" forState:UIControlStateNormal];
[diagnosticBtn setTitle:@"Diagnostic Report" forState:UIControlStateSelected];
[diagnosticBtn setTitleColor:[UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1.0f] forState:UIControlStateNormal];
[diagnosticBtn setTitleColor:[UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1.0f] forState:UIControlStateSelected];
[diagnosticBtn setFont:[UIFont fontWithName:@"Avenir-Medium" size:16]];
[diagnosticBtn setImage:[UIImage imageNamed:@"expand_blue.png"] forState:UIControlStateNormal];
[diagnosticBtn setImage:[UIImage imageNamed:@"collapse_blue.png"] forState:UIControlStateSelected];
[diagnosticBtn setImageEdgeInsets:UIEdgeInsetsMake(0, 290, 0, 0)];
[diagnosticBtn setTitleEdgeInsets:UIEdgeInsetsMake(0, -170, 0, 0)];
diagnosticBtn.tag = section;
[diagnosticBtn addTarget:self action:@selector(sectionHeaderBtnTapped:) forControlEvents:UIControlEventTouchUpInside];
[sectionHeaderView addSubview:diagnosticBtn];
UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(15, 0, 305, 1)];
view1.backgroundColor = [UIColor colorWithRed:217.0f/255.0f green:217.0f/255.0f blue:217.0f/255.0f alpha:1];
[sectionHeaderView addSubview:view1];
else if ([sectionName isEqualToString:@"Certification"])
UIButton *certificationBtn = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
[certificationBtn setTitle:@"Certification" forState:UIControlStateNormal];
[certificationBtn setTitle:@"Certification" forState:UIControlStateSelected];
[certificationBtn setTitleColor:[UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1.0f] forState:UIControlStateNormal];
[certificationBtn setTitleColor:[UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1.0f] forState:UIControlStateSelected];
[certificationBtn setFont:[UIFont fontWithName:@"Avenir-Medium" size:16]];
[certificationBtn setImage:[UIImage imageNamed:@"expand_blue.png"] forState:UIControlStateNormal];
[certificationBtn setImage:[UIImage imageNamed:@"collapse_blue.png"] forState:UIControlStateSelected];
[certificationBtn setImageEdgeInsets:UIEdgeInsetsMake(0, 290, 0, 0)];
[certificationBtn setTitleEdgeInsets:UIEdgeInsetsMake(0, -210, 0, 0)];
certificationBtn.tag = section;
[certificationBtn addTarget:self action:@selector(sectionHeaderBtnTapped:) forControlEvents:UIControlEventTouchUpInside];
[sectionHeaderView addSubview:certificationBtn];
UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(15, 0, 305, 1)];
view1.backgroundColor = [UIColor colorWithRed:217.0f/255.0f green:217.0f/255.0f blue:217.0f/255.0f alpha:1];
[sectionHeaderView addSubview:view1];
else if ([sectionName isEqualToString:@"Seller Declaration"])
UIButton *sellerDeclarationBtn = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
[sellerDeclarationBtn setTitle:@"Seller Declaration" forState:UIControlStateNormal];
[sellerDeclarationBtn setTitle:@"Seller Declaration" forState:UIControlStateSelected];
[sellerDeclarationBtn setTitleColor:[UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1.0f] forState:UIControlStateNormal];
[sellerDeclarationBtn setTitleColor:[UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1.0f] forState:UIControlStateSelected];
[sellerDeclarationBtn setFont:[UIFont fontWithName:@"Avenir-Medium" size:16]];
[sellerDeclarationBtn setImage:[UIImage imageNamed:@"expand_blue.png"] forState:UIControlStateNormal];
[sellerDeclarationBtn setImage:[UIImage imageNamed:@"collapse_blue.png"] forState:UIControlStateSelected];
[sellerDeclarationBtn setImageEdgeInsets:UIEdgeInsetsMake(0, 290, 0, 0)];
[sellerDeclarationBtn setTitleEdgeInsets:UIEdgeInsetsMake(0, -170, 0, 0)];
sellerDeclarationBtn.tag = section;
[sellerDeclarationBtn addTarget:self action:@selector(sectionHeaderBtnTapped:) forControlEvents:UIControlEventTouchUpInside];
[sectionHeaderView addSubview:sellerDeclarationBtn];
UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(15, 0, 305, 1)];
view1.backgroundColor = [UIColor colorWithRed:217.0f/255.0f green:217.0f/255.0f blue:217.0f/255.0f alpha:1];
[sectionHeaderView addSubview:view1];
else if ([sectionName isEqualToString:@"Others"])
UIButton *otherTrustFactorsBtn = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
[otherTrustFactorsBtn setTitle:@"Other Trust Factor" forState:UIControlStateNormal];
[otherTrustFactorsBtn setTitle:@"Other Trust Factor" forState:UIControlStateSelected];
[otherTrustFactorsBtn setTitleColor:[UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1.0f] forState:UIControlStateNormal];
[otherTrustFactorsBtn setTitleColor:[UIColor colorWithRed:51.0f/255.0f green:51.0f/255.0f blue:51.0f/255.0f alpha:1.0f] forState:UIControlStateSelected];
[otherTrustFactorsBtn setFont:[UIFont fontWithName:@"Avenir-Medium" size:16]];
[otherTrustFactorsBtn setImage:[UIImage imageNamed:@"expand_blue.png"] forState:UIControlStateNormal];
[otherTrustFactorsBtn setImage:[UIImage imageNamed:@"collapse_blue.png"] forState:UIControlStateSelected];
[otherTrustFactorsBtn setImageEdgeInsets:UIEdgeInsetsMake(0, 290, 0, 0)];
[otherTrustFactorsBtn setTitleEdgeInsets:UIEdgeInsetsMake(0, -165, 0, 0)];
otherTrustFactorsBtn.tag = section;
[otherTrustFactorsBtn addTarget:self action:@selector(sectionHeaderBtnTapped:) forControlEvents:UIControlEventTouchUpInside];
[sectionHeaderView addSubview:otherTrustFactorsBtn];
UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(15, 0, 305, 1)];
view1.backgroundColor = [UIColor colorWithRed:217.0f/255.0f green:217.0f/255.0f blue:217.0f/255.0f alpha:1];
[sectionHeaderView addSubview:view1];
[myHeader addSubview:sectionHeaderView];
return myHeader;
这是我在 UITableView 中的 numberOfRowsInSection 中填充数据的方式：
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
NSDictionary *sectionSuperDict = [self.sectionArray objectAtIndex:section];
NSString *sectionName = [sectionSuperDict objectForKey:@"name"];
NSDictionary *sectionDict = [sectionSuperDict objectForKey:@"value"];
UIView *sectionHeaderView = [self.tableView headerViewForSection:section];
UIButton *button;
for (UIView *subView in sectionHeaderView.subviews)
if (subView.tag == 1001)
for (UIView *subSubView in subView.subviews)
if ([subSubView isKindOfClass:[UIButton class]])
button = (UIButton *)subSubView;
NSInteger optionsCount = 0;
if ([sectionName isEqualToString:@"Verified Seller"])
else if ([sectionName isEqualToString:@"Pro-Seller"])
else if ([sectionName isEqualToString:@"Diagnostic"])
if (!button.selected)
optionsCount = 0;
else
if ([sectionDict isKindOfClass:[NSArray class]])
optionsCount = 1;
else
NSString *documentSource = [sectionDict objectForKey:@"document_source"];
if ([documentSource isEqualToString:@"none"])
optionsCount = 1;
else
optionsCount = 3;
if ([sectionDict objectForKey:@"documents"])
optionsCount +=1;
if ([sectionDict objectForKey:@"document_note"])
if (![[sectionDict objectForKey:@"document_note"] isEqualToString:@""])
optionsCount +=1;
else if ([sectionName isEqualToString:@"Certification"])
if (!button.selected)
optionsCount = 0;
else
if ([sectionDict isKindOfClass:[NSArray class]])
optionsCount = 1;
else
NSString *documentSource = [sectionDict objectForKey:@"document_source"];
if ([documentSource isEqualToString:@"none"])
optionsCount = 1;
else
optionsCount = 3;
if ([sectionDict objectForKey:@"documents"])
optionsCount +=1;
if ([sectionDict objectForKey:@"document_note"])
if (![[sectionDict objectForKey:@"document_note"] isEqualToString:@""])
optionsCount +=1;
else if ([sectionName isEqualToString:@"Seller Declaration"])
if (!button.selected)
optionsCount = 0;
else
if ([sectionDict isKindOfClass:[NSDictionary class]])
NSDictionary *valueDict = [sectionDict objectForKey:@"value"];
if ([valueDict isKindOfClass:[NSDictionary class]])
if ([[valueDict allKeys] count])
NSDictionary *acceptDict = [valueDict objectForKey:@"accept"];
if ([acceptDict isKindOfClass:[NSDictionary class]])
if ([[acceptDict allKeys] count])
NSString *acceptLabelString = [acceptDict objectForKey:@"label"];
if (![acceptLabelString isEqualToString:@""])
optionsCount +=1;
NSDictionary *declarationsDict = [valueDict objectForKey:@"declarations"];
if ([declarationsDict isKindOfClass:[NSDictionary class]])
optionsCount = optionsCount + [[declarationsDict allKeys] count];
else
optionsCount = 1;
else
optionsCount = 1;
else
optionsCount = 1;
else if ([sectionName isEqualToString:@"Others"])
if (!button.selected)
optionsCount = 0;
else
optionsCount = 1;
NSDictionary *serviceLogDict = [sectionDict objectForKey:@"service_log"];
if ([serviceLogDict isKindOfClass:[NSDictionary class]])
if ([[serviceLogDict allKeys] count])
//optionsCount +=1;
NSDictionary *registrationDict = [sectionDict objectForKey:@"registration"];
NSDictionary *insuranceDict = [sectionDict objectForKey:@"insurance"];
if ([registrationDict isKindOfClass:[NSDictionary class]] && [insuranceDict isKindOfClass:[NSDictionary class]])
if ([[registrationDict allKeys] count] || [[insuranceDict allKeys] count])
optionsCount +=1;
return optionsCount;
由于此处按钮返回 nil，而在更新第 5 节的 rowCount 为 1 之前，它会引发异常。应该怎么做才能让
[self.tableView headerViewForSection:section]
不为不可见部分返回 nil 吗？
【问题讨论】：
【参考方案1】：这不是您问题的答案，但可能是您的目的的解决方法：
我会在sectionArray 中的项目中添加一个键值对（例如："visible" = "true/false/0/1/..."）。在部分的按钮操作上修改此值。然后，读取numberOfRowsInSection... 方法中每个项目的值，以返回0 或sectionArray.count，具体取决于该部分当前是否可见。
希望对您有所帮助。
【讨论】：
谢谢你！虽然这不能回答问题，但它是解决问题的合适方法。我实现了类似的东西。非常感谢！【参考方案2】：在各个部分的任何地方访问表格视图标题的 Swift 解决方案
let tblHeaderView = tableView(YourTableView, viewForHeaderInSection: 0)
【讨论】：
以上是关于headerViewForSection：如果 Header View 或 section 在 iphone 上不可见，则返回 nil的主要内容，如果未能解决你的问题，请参考以下文章
如果我不使用 MFC，是不是需要 afxres.h？如何从 .RC 脚本中删除它？
如果在全页刷新 (FPR) 后未呈现文件，我如何有条件地在 h:head 中呈现 .js 文件？