爲什麼我的UIButton沒有被添加到我的單元格中？

Question

在我cellForRowAtIndexPath:方法，我有以下代碼：

 UIButton *signOutButton = [[UIButton alloc] init]; 

     [signOutButton addTarget:self action:@selector(logoutButtonTapped) forControlEvents:UIControlEventTouchUpInside]; 
     signOutButton.translatesAutoresizingMaskIntoConstraints = NO; 
     signOutButton.titleLabel.textColor = [UIColor colorWithRed:0/255.0 green:180/255.0 blue:35/255.0 alpha:1.0]; 
     signOutButton.titleLabel.text = @"Sign Out"; 

     [cell.contentView addSubview:signOutButton]; 

     [cell.contentView addConstraint:[NSLayoutConstraint constraintWithItem:signOutButton 
                    attribute:NSLayoutAttributeLeading 
                    relatedBy:NSLayoutRelationEqual 
                     toItem:cell.contentView 
                    attribute:NSLayoutAttributeLeft 
                    multiplier:1.0 
                     constant:50.0]]; 

     [cell.contentView addConstraint:[NSLayoutConstraint constraintWithItem:signOutButton 
                    attribute:NSLayoutAttributeTrailing 
                    relatedBy:NSLayoutRelationEqual 
                     toItem:cell.contentView 
                    attribute:NSLayoutAttributeRight 
                    multiplier:1.0 
                     constant:50.0]]; 

     [cell.contentView addConstraint:[NSLayoutConstraint constraintWithItem:signOutButton 
                    attribute:NSLayoutAttributeBottom 
                    relatedBy:NSLayoutRelationEqual 
                     toItem:cell.contentView 
                    attribute:NSLayoutAttributeBottom 
                    multiplier:1.0 
                     constant:-6.0]]; 

但它從來沒有顯示出來，當我加載細胞。我對自動佈局有點新鮮，所以任何人都可以弄清楚我做錯了什麼？

奇怪的是，如果我點擊按鈕應該執行的區域。

Answer 1

由於該方法在您按下時執行，因此您的按鈕似乎實際上已添加到單元格中。我認爲標題沒有設置。試着用 [signOutButton setTitle:@"Sign Out" forState:UIControlStateNormal]

Answer 2

你的按鈕替換 signOutButton.titleLabel.text = @"Sign Out" 是越來越增加，因爲你的標籤標題是沒有得到設置，因此你沒有看到它。你可以改變背景顏色，看看是不是在小區：

[signOutButton setBackgroundColor:[UIColor blueColor]]; 

，然後更改標題和顏色如下：

[signOutButton setTitle:@"Sign Out" forState:UIControlStateNormal]; 
[signOutButton setTitleColor:[UIColor colorWithRed:0/255.0 green:180/255.0 blue:35/255.0 alpha:1.0] forState:UIControlStateNormal]; 

這是你最後的代碼是怎麼回事的樣子：

UIButton *signOutButton = [[UIButton alloc] init]; 

[signOutButton addTarget:self action:@selector(logoutButtonTapped) forControlEvents:UIControlEventTouchUpInside]; 
signOutButton.translatesAutoresizingMaskIntoConstraints = NO; 
[signOutButton setTitle:@"Sign Out" forState:UIControlStateNormal]; 
[signOutButton setTitleColor:[UIColor colorWithRed:0/255.0 green:180/255.0 blue:35/255.0 alpha:1.0] forState:UIControlStateNormal]; 
[signOutButton setBackgroundColor:[UIColor blueColor]]; //just for testing, you can get rid of this line 

[cell.contentView addSubview:signOutButton]; 

[cell.contentView addConstraint:[NSLayoutConstraint constraintWithItem:signOutButton 
                  attribute:NSLayoutAttributeLeading 
                  relatedBy:NSLayoutRelationEqual 
                   toItem:cell.contentView 
                  attribute:NSLayoutAttributeLeft 
                  multiplier:1.0 
                   constant:50.0]]; 

[cell.contentView addConstraint:[NSLayoutConstraint constraintWithItem:signOutButton 
                  attribute:NSLayoutAttributeTrailing 
                  relatedBy:NSLayoutRelationEqual 
                   toItem:cell.contentView 
                  attribute:NSLayoutAttributeRight 
                  multiplier:1.0 
                   constant:50.0]]; 

[cell.contentView addConstraint:[NSLayoutConstraint constraintWithItem:signOutButton 
                  attribute:NSLayoutAttributeBottom 
                  relatedBy:NSLayoutRelationEqual 
                   toItem:cell.contentView 
                  attribute:NSLayoutAttributeBottom 
                  multiplier:1.0 
                   constant:-6.0]];