的TextField不被添加到滾動型

Question

當我輸入下面的代碼，不被顯示在滾動視圖我添加文本框：

.H

@interface FirstViewController : UIViewController <UIScrollViewDelegate> 
@property (strong, nonatomic) IBOutlet UIScrollView *scrollView; 
@property (strong, nonatomic) UITextField *firstField; 
@property (strong, nonatomic) UITextField *secondField; 
@property (strong, nonatomic) UITextField *thirdField; 

.M（viewDidLoad中）

self.firstField.placeholder = @"First"; 
self.firstField.textAlignment = NSTextAlignmentCenter; 
self.firstField.font = [UIFont fontWithName:@"Helvetica Neue Light" size:50.0]; 

self.secondField.placeholder = @"Second"; 
self.secondField.textAlignment = NSTextAlignmentCenter; 
self.secondField.font = [UIFont fontWithName:@"Helvetica Neue Light" size:50.0]; 

self.thirdField.placeholder = @"Third"; 
self.thirdField.textAlignment = NSTextAlignmentCenter; 
self.thirdField.font = [UIFont fontWithName:@"Helvetica Neue Light" size:50.0]; 

[self.scrollView addSubview:self.firstField]; 
[self.firstField autoPinEdgesToSuperviewEdgesWithInsets:UIEdgeInsetsZero excludingEdge:ALEdgeRight]; 
[self.firstField autoMatchDimension:ALDimensionWidth toDimension:ALDimensionWidth ofView:self.scrollView]; 
[self.firstField autoMatchDimension:ALDimensionHeight toDimension:ALDimensionHeight ofView:self.scrollView]; 

[self.scrollView addSubview:self.secondField]; 
[self.secondField autoPinEdge:ALEdgeLeft toEdge:ALEdgeRight ofView:self.firstField]; 
[self.secondField autoMatchDimension:ALDimensionWidth toDimension:ALDimensionWidth ofView:self.scrollView]; 
[self.secondField autoMatchDimension:ALDimensionHeight toDimension:ALDimensionHeight ofView:self.scrollView]; 

[self.scrollView addSubview:self.thirdField]; 
[self.thirdField autoPinEdge:ALEdgeLeft toEdge:ALEdgeRight ofView:self.secondField]; 
[self.thirdField autoPinEdgesToSuperviewEdgesWithInsets:UIEdgeInsetsZero excludingEdge:ALEdgeLeft]; 
[self.thirdField autoMatchDimension:ALDimensionWidth toDimension:ALDimensionWidth ofView:self.scrollView]; 
[self.thirdField autoMatchDimension:ALDimensionHeight toDimension:ALDimensionHeight ofView:self.scrollView]; 

self.automaticallyAdjustsScrollViewInsets = NO; 

我有self.scrollView是在一個scrollView的方式（在pageviewcontroller）。我使用PureLayout來定位文本字段，並且我非常確定我做的方式是正確的。有什麼我失蹤？

Answer 1

是你缺少一些代碼，如果你wan't添加的UITextField程序，您必須設置大小和位置你認爲，這樣的事情：

self.firstField.frame = CGRectMake(10, 200, 300, 40); 

我希望這會幫助你。

Answer 2

AutoLayout與UIScrollView的工作方式稍有不同：它與其contentView而不是其框架相關。 This is explained here。

默認情況下，您需要設置您的UIScrollView的contentView屬性，因爲它的CGSizeZero屬性。然後，如果你希望你的3個UITextfields並排出現，你將不得不改變它們的寬度約束，否則它們將填充整個contentSize。