以编程方式使用自动布局分页 UIScrollView？
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【中文标题】以编程方式使用自动布局分页 UIScrollView？【英文标题】：Paging UIScrollView with autolayout programmatically? 【发布时间】：2016-05-26 17:46:03 【问题描述】：我正在尝试复制重现此问题的答案：UIScrollView Paging Autolayout & Storyboard
以编程方式而不是使用界面生成器。
我遇到了一些约束冲突，我不知道为什么？
- (void)viewDidLoad
[super viewDidLoad];
// self.view is always the size of the application window
self.view = [[UIView alloc] init];
self.view.backgroundColor = [UIColor blackColor];
self.dummyView = [[UIView alloc] init];
self.dummyView.backgroundColor = [UIColor redColor];
[self.view addSubview:self.dummyView];
self.scrollView = [[UIScrollView alloc] init];
self.scrollView.backgroundColor = [UIColor blueColor];
[self.dummyView addSubview:self.scrollView];
self.contentView = [[UIView alloc] init];
self.contentView.backgroundColor = [UIColor orangeColor];
[self.scrollView addSubview:self.contentView];
self.pageView = [[UIView alloc] init];
self.pageView.backgroundColor = [UIColor yellowColor];
[self.contentView addSubview:self.pageView];
self.pageView2 = [[UIView alloc] init];
self.pageView2.backgroundColor = [UIColor greenColor];
[self.contentView addSubview:self.pageView2];
self.pageView3 = [[UIView alloc] init];
self.pageView3.backgroundColor = [UIColor purpleColor];
[self.contentView addSubview:self.pageView3];
// constraints must be added after the view heirarchy is established
[self addConstraints];
- (void) addConstraints
// Tell autoLayout to use my constraints (as opposed to inventing its own)
self.view.translatesAutoresizingMaskIntoConstraints = NO;
// **** Dummy View constraints:
// dummyView.leading = view.leading
NSLayoutConstraint* myConstraint = [NSLayoutConstraint
constraintWithItem:self.dummyView
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeLeading
multiplier:1.0
constant:0];
myConstraint.identifier = @"dummyView.leading = view.leading";
[self.view addConstraint:myConstraint];
// dummyView.trailing = view.trailing
myConstraint =[NSLayoutConstraint
constraintWithItem:self.dummyView
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:0];
myConstraint.identifier = @"dummyView.trailing = view.trailing";
[self.view addConstraint:myConstraint];
// dummyView.top = view.top
myConstraint =[NSLayoutConstraint
constraintWithItem:self.dummyView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:0];
myConstraint.identifier = @"dummyView.top = view.top";
[self.view addConstraint:myConstraint];
// dummyView.bottom = view.bottom
myConstraint =[NSLayoutConstraint
constraintWithItem:self.dummyView
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0];
myConstraint.identifier = @"dummyView.bottom = view.bottom";
[self.view addConstraint:myConstraint];
// **** Scroll View constraints
// scrollView.trailing = dummyView.trailing
myConstraint =[NSLayoutConstraint
constraintWithItem:self.scrollView
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self.dummyView
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:0];
myConstraint.identifier = @"scrollView.trailing = dummyView.trailing";
[self.dummyView addConstraint:myConstraint];
// scrollView.leading = dummyView.leading
myConstraint =[NSLayoutConstraint
constraintWithItem:self.scrollView
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.dummyView
attribute:NSLayoutAttributeLeading
multiplier:1.0
constant:0];
myConstraint.identifier = @"scrollView.leading = dummyView.leading";
[self.dummyView addConstraint:myConstraint];
// scrollView.Top = dummyView.top
myConstraint =[NSLayoutConstraint
constraintWithItem:self.scrollView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.dummyView
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:0];
myConstraint.identifier = @"scrollView.Top = dummyView.top";
[self.dummyView addConstraint:myConstraint];
// scrollView.bottom = dummyView.bottom
myConstraint =[NSLayoutConstraint
constraintWithItem:self.scrollView
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.dummyView
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0];
myConstraint.identifier = @"scrollView.bottom = dummyView.bottom";
[self.dummyView addConstraint:myConstraint];
// **** Content View Constraints
// contentView.width = dummyView.width * 3
myConstraint =[NSLayoutConstraint
constraintWithItem:self.contentView
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:self.dummyView
attribute:NSLayoutAttributeWidth
multiplier:3.0
constant:0];
myConstraint.identifier = @"contentView.width = dummyView.width * 3";
[self.dummyView addConstraint:myConstraint];
// contentView.height = dummyView.height
myConstraint =[NSLayoutConstraint
constraintWithItem:self.contentView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:self.dummyView
attribute:NSLayoutAttributeHeight
multiplier:1.0
constant:0];
myConstraint.identifier = @"contentView.height = dummyView.height";
[self.dummyView addConstraint:myConstraint];
// contentView.leading = scrollView.leading
myConstraint =[NSLayoutConstraint
constraintWithItem:self.contentView
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.scrollView
attribute:NSLayoutAttributeLeading
multiplier:1.0
constant:0];
myConstraint.identifier = @"contentView.leading = scrollView.leading";
[self.scrollView addConstraint:myConstraint];
// contentView.trailing = scrollView.trailing
myConstraint =[NSLayoutConstraint
constraintWithItem:self.contentView
attribute:NSLayoutAttributeTrailing
relatedBy:NSLayoutRelationEqual
toItem:self.scrollView
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:0];
myConstraint.identifier = @"contentView.trailing = scrollView.trailing";
[self.scrollView addConstraint:myConstraint];
// contentView.Top = scrollView.top
myConstraint =[NSLayoutConstraint
constraintWithItem:self.contentView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.scrollView
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:0];
myConstraint.identifier = @"contentView.Top = scrollView.top";
[self.scrollView addConstraint:myConstraint];
// contentView.bottom = scrollView.bottom
myConstraint =[NSLayoutConstraint
constraintWithItem:self.contentView
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.scrollView
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0];
myConstraint.identifier = @"contentView.bottom = scrollView.bottom";
[self.scrollView addConstraint:myConstraint];
// **** Page View 1 Constraints
// pageView.leading = contentView.leading
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.contentView
attribute:NSLayoutAttributeLeading
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView.leading = contentView.leading";
[self.contentView addConstraint:myConstraint];
// pageView.top = contenentView.top
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.contentView
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView.top = contenentView.top";
[self.contentView addConstraint:myConstraint];
// pageView.width = dummyView.width
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:self.dummyView
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView.width = dummyView.width";
[self.dummyView addConstraint:myConstraint];
// pageView.height = dummyView.height
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:self.dummyView
attribute:NSLayoutAttributeHeight
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView.height = dummyView.height";
[self.dummyView addConstraint:myConstraint];
// **** Page View 2 Constraints
// pageView2.height = pageView.height
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView2
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:self.pageView2
attribute:NSLayoutAttributeHeight
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView2.height = pageView.height";
[self.contentView addConstraint:myConstraint];
// pageView2.width = pageView.width
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView2
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:self.pageView
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:0];
myConstraint.identifier = @" pageView2.width = pageView.width";
[self.contentView addConstraint:myConstraint];
// pageView2.top = pageView.top
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView2
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.pageView
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView2.top = pageView.top";
[self.contentView addConstraint:myConstraint];
// pageView2.leading = pageView.trailing
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView2
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.pageView
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView2.leading = pageView.trailing";
[self.contentView addConstraint:myConstraint];
// **** Page View 3 Constraints
// pageView3.height = pageView.height
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView3
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:self.pageView
attribute:NSLayoutAttributeHeight
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView3.height = pageView.height";
[self.contentView addConstraint:myConstraint];
// pageView3.width = pageView.width
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView3
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:self.pageView
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView3.width = pageView.width";
[self.contentView addConstraint:myConstraint];
// pageView3.Top = pageView.Top
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView3
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.pageView
attribute:NSLayoutAttributeTop
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView3.Top = pageView.Top";
[self.contentView addConstraint:myConstraint];
// pageView3.leading = pageView2.trailing
myConstraint =[NSLayoutConstraint
constraintWithItem:self.pageView3
attribute:NSLayoutAttributeLeading
relatedBy:NSLayoutRelationEqual
toItem:self.pageView2
attribute:NSLayoutAttributeTrailing
multiplier:1.0
constant:0];
myConstraint.identifier = @"pageView3.leading = pageView2.trailing";
[self.contentView addConstraint:myConstraint];
错误是：
Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x134e1c340 h=--& v=--& UIView:0x134e3e740.midX ==>",
"<NSAutoresizingMaskLayoutConstraint:0x134d47a20 h=--- v=--- H:[UIWindow:0x134e3a6c0(375)]>",
"<NSLayoutConstraint:0x134e4c960 H:|-(0)-[UIView:0x134e3bdf0](LTR) (Names: '|':UIWindow:0x134e3a6c0 )>",
"<NSLayoutConstraint:0x134e4ca00 UIView:0x134e3bdf0.right == UIWindow:0x134e3a6c0.right>",
"<NSLayoutConstraint:0x134e3f150 'dummyView.leading = view.leading' H:|-(0)-[UIView:0x134e3cb00] (Names: '|':UIView:0x134e3bdf0 )>",
"<NSLayoutConstraint:0x134e3f480 'dummyView.trailing = view.trailing' UIView:0x134e3cb00.trailing == UIView:0x134e3bdf0.trailing>",
"<NSLayoutConstraint:0x134e3fc60 'pageView.leading = contentView.leading' H:|-(0)-[UIView:0x134e3e740] (Names: '|':UIView:0x134e3e450 )>",
"<NSLayoutConstraint:0x134e3fd30 'pageView.width = dummyView.width' UIView:0x134e3e740.width == UIView:0x134e3cb00.width>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x134e3fc60 'pageView.leading = contentView.leading' H:|-(0)-[UIView:0x134e3e740] (Names: '|':UIView:0x134e3e450 )>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2016-05-26 10:28:55.062 autolayouttest[682:208278] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x134d3e930 h=--& v=--& UIView:0x134e3e740.midY ==>",
"<NSAutoresizingMaskLayoutConstraint:0x134d45af0 h=--- v=--- V:[UIWindow:0x134e3a6c0(667)]>",
"<NSLayoutConstraint:0x134e4c910 V:|-(0)-[UIView:0x134e3bdf0] (Names: '|':UIWindow:0x134e3a6c0 )>",
"<NSLayoutConstraint:0x134e4c9b0 UIView:0x134e3bdf0.bottom == UIWindow:0x134e3a6c0.bottom>",
"<NSLayoutConstraint:0x134e3f540 'dummyView.bottom = view.bottom' UIView:0x134e3cb00.bottom == UIView:0x134e3bdf0.bottom>",
"<NSLayoutConstraint:0x134e3f4d0 'dummyView.top = view.top' V:|-(0)-[UIView:0x134e3cb00] (Names: '|':UIView:0x134e3bdf0 )>",
"<NSLayoutConstraint:0x134e3f9c0 'pageView.height = dummyView.height' UIView:0x134e3e740.height == UIView:0x134e3cb00.height>",
"<NSLayoutConstraint:0x134e3fce0 'pageView.top = contenentView.top' V:|-(0)-[UIView:0x134e3e740] (Names: '|':UIView:0x134e3e450 )>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x134e3fce0 'pageView.top = contenentView.top' V:|-(0)-[UIView:0x134e3e740] (Names: '|':UIView:0x134e3e450 )>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x134d47a20 h=--- v=--- H:[UIWindow:0x134e3a6c0(375)]>",
"<NSAutoresizingMaskLayoutConstraint:0x134d476e0 h=--& v=--& UIScrollView:0x135000000.midX ==>",
"<NSLayoutConstraint:0x134e4c960 H:|-(0)-[UIView:0x134e3bdf0](LTR) (Names: '|':UIWindow:0x134e3a6c0 )>",
"<NSLayoutConstraint:0x134e4ca00 UIView:0x134e3bdf0.right == UIWindow:0x134e3a6c0.right>",
"<NSLayoutConstraint:0x134e3f150 'dummyView.leading = view.leading' H:|-(0)>",
"<NSLayoutConstraint:0x134e3f480 'dummyView.trailing = view.trailing' UIView:0x134e3cb00.trailing == UIView:0x134e3bdf0.trailing>",
"<NSLayoutConstraint:0x134e3f610 'scrollView.leading = dummyView.leading' H:|-(0)-[UIScrollView:0x135000000] (Names: '|':UIView:0x134e3cb00 )>",
"<NSLayoutConstraint:0x134e3f590 'scrollView.trailing = dummyView.trailing' UIScrollView:0x135000000.trailing == UIView:0x134e3cb00.trailing>"
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x134e3f590 'scrollView.trailing = dummyView.trailing' UIScrollView:0x135000000.trailing == UIView:0x134e3cb00.trailing>
Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2016-05-26 10:28:55.067 autolayouttest[682:208278] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSAutoresizingMaskLayoutConstraint:0x134d47a20 h=--- v=--- H:[UIWindow:0x134e3a6c0(375)]>",
"<NSAutoresizingMaskLayoutConstraint:0x134d43660 h=--& v=--& UIView:0x134e3cb00.midX ==>",
"<NSLayoutConstraint:0x134e4c960 H:|-(0)-[UIView:0x134e3bdf0](LTR) (Names: '|':UIWindow:0x134e3a6c0 )>",
"<NSLayoutConstraint:0x134e4ca00 UIView:0x134e3bdf0.right == UIWindow:0x134e3a6c0.right>",
"<NSLayoutConstraint:0x134e3f150 'dummyView.leading = view.leading' H:|-(0)-[UIView:0x134e3cb00] (Names: '|':UIView:0x134e3bdf0 )>",
"<NSLayoutConstraint:0x134e3f480 'dummyView.trailing = view.trailing' UIView:0x134e3cb00.trailing == UIView:0x134e3bdf0.trailing>"
如有任何帮助，我们将不胜感激。谢谢！
【问题讨论】：
【参考方案1】：// 告诉 autoLayout 使用我的约束（而不是发明它的 自己的） self.view.translatesAutoresizingMaskIntoConstraints = NO;
必须对所有以编程方式创建的视图执行此操作。由于您尚未创建 self.view，因此不应为此视图更改 translatesAutoresizingMaskIntoConstraints。
// Tell autoLayout to use my constraints (as opposed to inventing its own)
self.dummyView.translatesAutoresizingMaskIntoConstraints = NO;
self.contentView.translatesAutoresizingMaskIntoConstraints = NO;
self.scrollView.translatesAutoresizingMaskIntoConstraints = NO;
self.pageView.translatesAutoresizingMaskIntoConstraints = NO;
self.pageView2.translatesAutoresizingMaskIntoConstraints = NO;
self.pageView3.translatesAutoresizingMaskIntoConstraints = NO;
【讨论】：
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