constraints

Autolayout animate constraint does not animate subviews

由 怎甘沉沦 提交于 2019-12-07 06:11:14
问题 I have a UIView which has a UILabel as subview in it. Now I change the width of the UIView with an animation (changing constant property of constraint) and call layoutIfNeeded in UIView animate...) The view is resizing normal, but the UILabel (subview) changes the font size to the 'end'-size but didn't animate correctly like the uiview. According to the WWDC 2012 session the subviews should animate if only the constant of the superview gets changed. The UILabel has a minimum font scale of 0,1

Auto layout internal error happening when a view is dismissed

由 核能气质少年 提交于 2019-12-07 05:04:27
问题 I'm getting a funny error when I dismiss some views on which I have some constraints. Auto layout internal error. Cannot find an outgoing row head for incoming head AppName.ViewName:0x7fc072ed8ef0.Width{id: 6805} during optimization of variable with near-zero coefficient, which should never happen. I'm getting this bug on several views to which I'm adding these constraints. One variation of this error message is the following: Auto layout internal error. Cannot find an outgoing row head for

How to find the crashing constraint?

由 倖福魔咒の 提交于 2019-12-07 04:50:00
问题 Sometimes I keep getting errors like these - without any hint to which TextView or Button is meant: 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

Named CONSTRAINT benefits

由 断了今生、忘了曾经 提交于 2019-12-07 03:30:46
问题 I'm learning SQL and stumbled about CONSTRAINT. I can define them like this: CREATE TABLE products ( product_no integer, name text, price numeric CHECK (price > 0) ); and like this: CREATE TABLE products ( product_no integer, name text, price numeric CONSTRAINT positive_price CHECK (price > 0) ); Why do I give them names? or Why I should or should not give them names? As I can see in this example and most situations in my mind I can't reuse them. So what is the benefit of giving a name to a

When is a value type / reference type constraint useful in C#?

由 ￡可爱￡侵袭症＋ 提交于 2019-12-07 03:28:56
问题 I'm looking for simple examples that demonstrate when the value type / reference type constraints are useful. ... where T : struct // when is this useful? ... where T : class // and what about this? I remember seeing some very nice examples in the past but I just can't find them. 回答1: It allows you to use as operator on T if it is T:class . It forbids you to compare T with null if T is T:struct . Note that if you omit T:class then you can compare T to null even when T is a value type. [Note:

Constraints in R Multiple Integer Linear Programming

由 别来无恙 提交于 2019-12-07 02:26:25
I am working on some code in R to optimize my fantasy football lineup but I am having some difficulty with one constraint. I basically have a list of players, their position, expected points, and cost. Roster must include: 1 QB 2 RB 2 WR 1 TE 1 FLEX (either a RB, WR, or TE) Total cost under $200 My issue is that my code wants to pick the FLEX position as player it already selected as a WR, RB or TE. Here is the code I am using, I have a table that I imported with columns for player, position, points, and cost. In the table, any RB, WR, or TE is duplicated with the position as FLEX. I tried to

SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails - Laravel

由 旧巷老猫 提交于 2019-12-07 01:42:36
问题 I know that this question has already been asked, but I still can't find what I'm doing wrong. I'm using the framework Laravel. I have 2 tables (Users and Locations). When I want to create a User, I get the error message: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails ( festival_aid . users , CONSTRAINT fk_users_locations1 FOREIGN KEY ( location_id ) REFERENCES locations ( location_id ) ON DELETE CASCADE ON UPDATE NO

How to Add Constraint for view inside stack view

由 谁说我不能喝 提交于 2019-12-07 00:12:02
问题 I have one stack view that contains with 4 buttons. And each button I also add subview to that. The subview of that 4 buttons, I try to program to add constraint into it. Some constraint such as .Trailing .Leading .Top .Bottom I cannot add to it by error constraint and stack view problem. How any solution to add that constraints to subview of stackview. if have any sample it's really good for me. thank in advance 回答1: UIStackView's power is to reduce your using of constrains, just give it

“Column ’x’ does not exist” error for string literal ’x’ in PostgreSQL [duplicate]

由 徘徊边缘 提交于 2019-12-06 23:36:28
问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Column ‘mary’ does not exist I need to check the values that can be accepted to a column through a check constraint. I need to use the check constraint, because this is for a college assignment. I use this code to create and add the constraint to the table. CREATE TABLE Ereignis( E_Id Serial PRIMARY KEY, Typ varchar(15), Zeitpunkt timestamp, Ort varchar(32), Anzahl_Pers int ); ALTER TABLE Ereignis ADD CONSTRAINT

C# overloading with generics: bug or feature?

由 天涯浪子 提交于 2019-12-06 22:12:39
问题 Let's have a following simplified example: void Foo<T>(IEnumerable<T> collection, params T[] items) { // ... } void Foo<C, T>(C collection, T item) where C : ICollection<T> { // ... } void Main() { Foo((IEnumerable<int>)new[] { 1 }, 2); } Compiler says: The type 'System.Collections.Generic.IEnumerable' cannot be used as type parameter 'C' in the generic type or method 'UserQuery.Foo(C, T)'. There is no implicit reference conversion from 'System.Collections.Generic.IEnumerable' to 'System
订阅 constraints