iOS - 无法使用progressView

Question

我尝试使用约束将progressView放在UIAlertController中，以便在iPhone或iPad上获得良好的视觉效果。

alert = [UIAlertController
             alertControllerWithTitle:title
             message:message
             preferredStyle:UIAlertControllerStyleAlert];

    UIAlertAction* cancelButton = [UIAlertAction
                               actionWithTitle:titleCancel
                               style:UIAlertActionStyleDefault
                               handler:cancelBlock];


    [alert addAction:cancelButton];


    UIProgressView* progressView = [[UIProgressView alloc] init];
    progressView.progress = 0.0;
    progressView.tintColor = UIColor.blueColor;
    [alert.view addSubview:progressView];


    UILayoutGuide *margin = alert.view.layoutMarginsGuide;
    [alert.view setAutoresizingMask:UIViewAutoresizingNone];
    [progressView.heightAnchor constraintEqualToConstant:5].active = YES;
    [progressView.widthAnchor constraintEqualToAnchor:margin.widthAnchor multiplier:0.75].active = YES;
    [progressView.centerXAnchor constraintEqualToAnchor:margin.centerXAnchor].active = YES;
    [progressView.centerYAnchor constraintEqualToAnchor:margin.centerYAnchor].active = YES;

    [self presentViewController:alert animated:YES completion:nil];

我想要实现这样的东西（que紫色方块是使用alertViewController，只是一个例子......）：

这是日志......我做错了......为什么会遇到与约束的冲突？

2017-05-09 18:17:28.657982 Myapp[1457:1442554] [Common] _BSMachError: port a0a3; (os/kern) invalid capability (0x14) "Unable to insert COPY_SEND"
2017-05-09 18:17:28.659300 Myapp[1457:1442554] [Common] _BSMachError: port a0a3; (os/kern) invalid name (0xf) "Unable to deallocate send right"
2017-05-09 18:17:28.709082 Myapp[1457:1442554] [LayoutConstraints] 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:0x17048be00 h=--& v=--& UIProgressView:0x1013a44b0.height == 2   (active)>",
    "<NSLayoutConstraint:0x17449cb60 UIProgressView:0x1013a44b0.height == 5   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x17449cb60 UIProgressView:0x1013a44b0.height == 5   (active)>

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.
2017-05-09 18:17:28.712681 Myapp[1457:1442554] [LayoutConstraints] 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:0x170490310 h=--& v=--& UIProgressView:0x1013a44b0.midY == 1   (active)>",
    "<NSLayoutConstraint:0x17449fef0 UIView:0x1013a56e0.height >= 44   (active)>",
    "<NSLayoutConstraint:0x17449b2b0 _UIAlertControllerView:0x1013a5a40'Myapp'.height == UIView:0x1013a56e0.height   (active)>",
    "<NSLayoutConstraint:0x174681e50 UIProgressView:0x1013a44b0.centerY == UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'.centerY   (active)>",
    "<NSLayoutConstraint:0x174681e00 'UIView-bottomMargin-guide-constraint' V:[UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide']-(8)-|   (active, names: '|':_UIAlertControllerView:0x1013a5a40'Myapp' )>",
    "<NSLayoutConstraint:0x174681bd0 'UIView-topMargin-guide-constraint' V:|-(8)-[UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide']   (active, names: '|':_UIAlertControllerView:0x1013a5a40'Myapp' )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x17449fef0 UIView:0x1013a56e0.height >= 44   (active)>

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.
2017-05-09 18:17:28.715180 Myapp[1457:1442554] [LayoutConstraints] 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:0x170490310 h=--& v=--& UIProgressView:0x1013a44b0.midY == 1   (active)>",
    "<NSLayoutConstraint:0x174681e50 UIProgressView:0x1013a44b0.centerY == UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'.centerY   (active)>",
    "<NSLayoutConstraint:0x174681bd0 'UIView-topMargin-guide-constraint' V:|-(8)-[UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide']   (active, names: '|':_UIAlertControllerView:0x1013a5a40'Myapp' )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x174681e50 UIProgressView:0x1013a44b0.centerY == UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'.centerY   (active)>

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.
2017-05-09 18:17:28.717844 Myapp[1457:1442554] [LayoutConstraints] 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:0x170490f40 h=--& v=--& UIProgressView:0x1013a44b0.midX == 0   (active)>",
    "<NSAutoresizingMaskLayoutConstraint:0x170495270 h=--& v=--& UIProgressView:0x1013a44b0.width == 0   (active)>",
    "<NSLayoutConstraint:0x174681db0 UIProgressView:0x1013a44b0.width == 0.75*UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'.width   (active)>",
    "<NSLayoutConstraint:0x174681f40 UIProgressView:0x1013a44b0.centerX == UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'.centerX   (active)>",
    "<NSLayoutConstraint:0x174681c20 'UIView-leftMargin-guide-constraint' H:|-(8)-[UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UIAlertControllerView:0x1013a5a40'Myapp' )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x174681f40 UIProgressView:0x1013a44b0.centerX == UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'.centerX   (active)>

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.
2017-05-09 18:17:28.720158 Myapp[1457:1442554] [LayoutConstraints] 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:0x170495270 h=--& v=--& UIProgressView:0x1013a44b0.width == 0   (active)>",
    "<NSLayoutConstraint:0x170288840 UIView:0x1013a56e0.width == 270   (active)>",
    "<NSLayoutConstraint:0x174499eb0 _UIAlertControllerView:0x1013a5a40'Myapp'.width >= UIView:0x1013a56e0.width   (active)>",
    "<NSLayoutConstraint:0x174681db0 UIProgressView:0x1013a44b0.width == 0.75*UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'.width   (active)>",
    "<NSLayoutConstraint:0x174681c20 'UIView-leftMargin-guide-constraint' H:|-(8)-[UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide'](LTR)   (active, names: '|':_UIAlertControllerView:0x1013a5a40'Myapp' )>",
    "<NSLayoutConstraint:0x174681f90 'UIView-rightMargin-guide-constraint' H:[UILayoutGuide:0x174389170'UIViewLayoutMarginsGuide']-(8)-|(LTR)   (active, names: '|':_UIAlertControllerView:0x1013a5a40'Myapp' )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x170288840 UIView:0x1013a56e0.width == 270   (active)>

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.

Answer 1

首先，我不认为为进度视图添加约束是一个好主意。因为它被添加到呈现的UIAlertController中。

如果要添加progressView，则需要跟踪进度并更新需要在主线程上完成的进度，因此每次进行任何繁重操作时都可能会影响UI更新（进度）。这必须由GCD正确处理

以下方法将有助于解决您的问题

dispatch_async(dispatch_get_main_queue(), ^{
UIAlertController * alertCont = [UIAlertController alertControllerWithTitle:@"Test" message:@"Test message" preferredStyle:UIAlertControllerStyleAlert];

    UIProgressView * progresbar = [[UIProgressView alloc]initWithProgressViewStyle:UIProgressViewStyleDefault];
    [progresbar setProgress:5.0 animated:YES];
    progresbar.frame = CGRectMake(10, 40, 250, 0);
    [alertCont.view addSubview:progresbar];
    [topController presentViewController:alertCont animated:YES completion:nil];
});

Answer 2

您不应该设置相对于AlertviewController视图的约束。而是使用AlertviewController - ＆gt;查看 - ＆gt;子视图[0]设置约束。

例如，要设置UIAlertController的宽度：

for constraint in self.alertView.subviews[0].constraints {
  if constraint.firstAttribute == NSLayoutAttribute.width && constraint.constant == 270{
    NSLayoutConstraint.deactivate([constraint])
    break
  }
}

let widthConstraint:NSLayoutConstraint = NSLayoutConstraint(item: self.view.subviews[0], attribute:
  NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 120.0)

self.alertview.subviews[0].addConstraint(widthConstraint)