在 IB 中仅更改 iPhone 4 的约束值
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【中文标题】在 IB 中仅更改 iPhone 4 的约束值【英文标题】：Change the value of constraint for only iPhone 4 in IB 【发布时间】：2016-05-24 10:45:43 【问题描述】：如何仅在一台设备上更改约束值。 例如，我想为除 iPhone 4 之外的所有 iPhone 显示一个高度为 400px 的按钮，我会以 300px 显示它？
【问题讨论】：
【参考方案1】：最好的解决方案是创建一个继承自 NSLayoutConstraint 类的新类并添加下面的属性，这样您就可以更改常量、乘数以及停用每个设备的约束以及所有这些在界面构建器中：
import UIKit
/**
* This class used to modify easly the constraint for each device iPhone 4, iPhone 5, iPhone 6 or iPhone 6 Plus
* You can modify the constant, the multiplier and also active / deactive the constraint for each device
* You should modify this properties only in the storyboard
*/
@IBDesignable
public class LayoutConstraint: NSLayoutConstraint
// MARK: ?3¨5
/**
* The constant for device with 3.5 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?3¨5_const: CGFloat = 0
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 480
constant = ?3¨5_const
/**
* The multiplier for device with 3.5 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?3¨5_multip: CGFloat = 0
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 480
self.setValue(?3¨5_multip, forKey: "multiplier")
/**
* The boolean to active deative constraint for device with 3.5 insh size
* The default value is true.
*/
@IBInspectable
public var ?3¨5_active: Bool = true
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 480
active = ?3¨5_active
// MARK: ?4¨0
/**
* The constant for device with 4.0 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?4¨0_const: CGFloat = 0
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 568
constant = ?4¨0_const
/**
* The multiplier for device with 4.0 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?4¨0_multip: CGFloat = 0
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 568
self.setValue(?4¨0_multip, forKey: "multiplier")
/**
* The boolean to active deative constraint for device with 4.0 insh size
* The default value is true.
*/
@IBInspectable
public var ?4¨0_active: Bool = true
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 568
active = ?4¨0_active
// MARK: ?4¨7
/**
* The constant for device with 4.7 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?4¨7_const: CGFloat = 0
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 667
constant = ?4¨7_const
/**
* The multiplier for device with 4.7 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?4¨7_multip: CGFloat = 0
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 667
self.setValue(?4¨7_multip, forKey: "multiplier")
/**
* The boolean to active deative constraint for device with 4.7 insh size
* The default value is true.
*/
@IBInspectable
public var ?4¨7_active: Bool = true
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 667
active = ?4¨7_active
// MARK: ?5¨5
/**
* The constant for device with 5.5 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?5¨5_const: CGFloat = 0
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 736
constant = ?5¨5_const
/**
* The multiplier for device with 5.5 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?5¨5_multip: CGFloat = 0
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 736
self.setValue(?5¨5_multip, forKey: "multiplier")
/**
* The boolean to active / deactive constraint for device with 5.5 insh size
* The default value is true.
*/
@IBInspectable
public var ?5¨5_active: Bool = true
didSet
if CGRectGetMaxY(UIScreen.mainScreen().bounds) == 736
active = ?5¨5_active
【讨论】：
@HamzaGhazouani 当我们更改 IB 中的值时它会自动更新吗？ @BadhanGanesh 当你更改 IB 中的值时，你应该运行项目来查看结果【参考方案2】：您可以为您的约束设置插座并根据您正在运行的设备更改其值。即如果是 iphone4，则为 300 像素，否则为 400 像素，使用插座的“constant”属性
【讨论】：
【参考方案3】：您可以取消该按钮的高度限制。然后你可以检测设备是否是 iphone 4 然后你可以改变它的约束插座的constant 之类的东西，
self.heightConstraint.constant = 300;
仅用于连接约束出口ctrl + drag from that constraint to class
您可以通过获取屏幕大小来检测设备。
if ([ [ UIScreen mainScreen ] bounds ].size.height == 480.00)
NSLog(@"this is iphn 4");
self.heightConstraint.constant = 300;
希望这会有所帮助:)
【讨论】：
【参考方案4】：首先创建按钮高度约束的对象(btnConstHeight)
if ([ [ UIScreen mainScreen ] bounds ].size.height == 480.00)
self.btnConstHeight.constant = 300;
else
self.btnConstHeight.constant = 400;
【讨论】：
【参考方案5】：@Hamza 答案的 Swift 4 版本
import Foundation
import UIKit
/**
* This class used to modify easly the constraint for each device iPhone 4, iPhone 5, iPhone 6 or iPhone 6 Plus
* You can modify the constant, the multiplier and also active / deactive the constraint for each device
* You should modify this properties only in the storyboard
*/
@IBDesignable
public class LayoutConstraint: NSLayoutConstraint
// MARK: ?3¨5
/**
* The constant for device with 3.5 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?3¨5_const: CGFloat = 0
didSet
if UIScreen.main.bounds.maxY == 480
constant = ?3¨5_const
/**
* The multiplier for device with 3.5 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?3¨5_multip: CGFloat = 0
didSet
if UIScreen.main.bounds.maxY == 480
self.setValue(?3¨5_multip, forKey: "multiplier")
/**
* The boolean to active deative constraint for device with 3.5 insh size
* The default value is true.
*/
@IBInspectable
public var ?3¨5_active: Bool = true
didSet
if UIScreen.main.bounds.maxY == 480
isActive = ?3¨5_active
// MARK: ?4¨0
/**
* The constant for device with 4.0 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?4¨0_const: CGFloat = 0
didSet
if UIScreen.main.bounds.maxY == 568
constant = ?4¨0_const
/**
* The multiplier for device with 4.0 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?4¨0_multip: CGFloat = 0
didSet
if UIScreen.main.bounds.maxY == 568
self.setValue(?4¨0_multip, forKey: "multiplier")
/**
* The boolean to active deative constraint for device with 4.0 insh size
* The default value is true.
*/
@IBInspectable
public var ?4¨0_active: Bool = true
didSet
if UIScreen.main.bounds.maxY == 568
isActive = ?4¨0_active
// MARK: ?4¨7
/**
* The constant for device with 4.7 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?4¨7_const: CGFloat = 0
didSet
if UIScreen.main.bounds.maxY == 667
constant = ?4¨7_const
/**
* The multiplier for device with 4.7 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?4¨7_multip: CGFloat = 0
didSet
if UIScreen.main.bounds.maxY == 667
self.setValue(?4¨7_multip, forKey: "multiplier")
/**
* The boolean to active deative constraint for device with 4.7 insh size
* The default value is true.
*/
@IBInspectable
public var ?4¨7_active: Bool = true
didSet
if UIScreen.main.bounds.maxY == 667
isActive = ?4¨7_active
// MARK: ?5¨5
/**
* The constant for device with 5.5 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?5¨5_const: CGFloat = 0
didSet
if UIScreen.main.bounds.maxY == 736
constant = ?5¨5_const
/**
* The multiplier for device with 5.5 insh size
* The default value is the value of the constant of the constraint.
*/
@IBInspectable
public var ?5¨5_multip: CGFloat = 0
didSet
if UIScreen.main.bounds.maxY == 736
self.setValue(?5¨5_multip, forKey: "multiplier")
/**
* The boolean to active / deactive constraint for device with 5.5 insh size
* The default value is true.
*/
@IBInspectable
public var ?5¨5_active: Bool = true
didSet
if UIScreen.main.bounds.maxY == 736
isActive = ?5¨5_active
【讨论】：
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