在文本字段中居中对齐占位符
Center align placeholder in textfield
我知道这个问题被问过很多次,但由于 drawinrect 已弃用,我在 ios 中需要这个 8.As 我有一个文本字段,我需要居中对齐的占位符,剩下的测试align.Please帮帮我。
创建 IBOutlet 并将其连接到您的文本字段。在YourViewController.m
@interface YourViewController () <UITextFieldDelegate>
@property (weak, nonatomic) IBOutlet UITextField *txt;
在你的 viewDidLoad
self.txt.delegate=self;
self.txt.textAlignment=NSTextAlignmentCenter;
编写此委托方法..每次文本字段中的文本更改时调用此方法。
- (BOOL) textField: (UITextField *)theTextField shouldChangeCharactersInRange: (NSRange)range replacementString: (NSString *)string {
NSRange textFieldRange = NSMakeRange(0, [self.txt.text length]);
// Check If textField is empty. If empty align your text field to center, so that placeholder text will show center aligned
if (NSEqualRanges(range, textFieldRange) && [string length] == 0) {
self.txt.textAlignment=NSTextAlignmentCenter;
}
else //else align textfield to left.
{
self.txt.textAlignment=NSTextAlignmentLeft;
}
return YES;
}
您可以通过将 attributedPlaceholder
与对齐设置为 .center
:
的段落样式一起使用来使占位符居中
let centeredParagraphStyle = NSMutableParagraphStyle()
centeredParagraphStyle.alignment = .center
textField.attributedPlaceholder = NSAttributedString(
string: "Placeholder",
attributes: [.paragraphStyle: centeredParagraphStyle]
)
@Clay Ellis 的回答是正确的,这里是 Objective-C:
UITextField* field = [[UITextField alloc] initWithFrame: fieldRect];
NSTextAlignment alignment = NSTextAlignmentCenter;
NSMutableParagraphStyle* alignmentSetting = [[NSMutableParagraphStyle alloc] init];
alignmentSetting.alignment = alignment;
NSDictionary *attributes = @{NSParagraphStyleAttributeName : alignmentSetting};
NSAttributedString *str = [[NSAttributedString alloc] initWithString:placeholder attributes: attributes];
field.attributedPlaceholder = str;
based on Clay Ellis answer
详情
- Xcode 版本 10.2.1 (10E1001),Swift 5
解决方案 1
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
textField.attributedText = NSAttributedString(string: placeholder, attributes: [.paragraphStyle: paragraphStyle])
解决方案 2
import Foundation
extension String {
func toAttributed(alignment: NSTextAlignment) -> NSAttributedString {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
return toAttributed(attributes: [.paragraphStyle: paragraphStyle])
}
func toAttributed(attributes: [NSAttributedString.Key : Any]? = nil) -> NSAttributedString {
return NSAttributedString(string: self, attributes: attributes)
}
}
解决方案2的用法
// Way 1
textField.attributedPlaceholder = text.attributedString(alignment: .center)
// Way 2
textField.attributedPlaceholder = "title".attributedString(alignment: .center)
完整样本
Do not forget to add the solution code here
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let textField = UITextField()
textField.borderStyle = .roundedRect
view.addSubview(textField)
//textField.attributedPlaceholder = getAttributedString1()
textField.attributedPlaceholder = getAttributedString2()
textField.translatesAutoresizingMaskIntoConstraints = false
textField.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 24).isActive = true
textField.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 16).isActive = true
view.safeAreaLayoutGuide.rightAnchor.constraint(equalTo: textField.rightAnchor, constant: 16).isActive = true
}
private func getAttributedString1() -> NSAttributedString {
return "placeholder".toAttributed(alignment: .center)
}
private func getAttributedString2() -> NSAttributedString {
var attributes = [NSAttributedString.Key: Any]()
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
attributes[.paragraphStyle] = paragraphStyle
attributes[.font] = UIFont.systemFont(ofSize: 12, weight: .bold)
attributes[.foregroundColor] = UIColor.black.withAlphaComponent(0.5)
attributes[.underlineStyle] = NSUnderlineStyle.single.rawValue
attributes[.underlineColor] = UIColor.red
return "placeholder".toAttributed(attributes: attributes)
}
}
结果
@Clay Ellis 在 Swift 5
中的回答
let centeredParagraphStyle = NSMutableParagraphStyle()
centeredParagraphStyle.alignment = .center
let attributedPlaceholder = NSAttributedString(string: "Placeholder", attributes: [NSAttributedString.Key.paragraphStyle: centeredParagraphStyle])
textField.attributedPlaceholder = attributedPlaceholder
我知道这个问题被问过很多次,但由于 drawinrect 已弃用,我在 ios 中需要这个 8.As 我有一个文本字段,我需要居中对齐的占位符,剩下的测试align.Please帮帮我。
创建 IBOutlet 并将其连接到您的文本字段。在YourViewController.m
@interface YourViewController () <UITextFieldDelegate>
@property (weak, nonatomic) IBOutlet UITextField *txt;
在你的 viewDidLoad
self.txt.delegate=self;
self.txt.textAlignment=NSTextAlignmentCenter;
编写此委托方法..每次文本字段中的文本更改时调用此方法。
- (BOOL) textField: (UITextField *)theTextField shouldChangeCharactersInRange: (NSRange)range replacementString: (NSString *)string {
NSRange textFieldRange = NSMakeRange(0, [self.txt.text length]);
// Check If textField is empty. If empty align your text field to center, so that placeholder text will show center aligned
if (NSEqualRanges(range, textFieldRange) && [string length] == 0) {
self.txt.textAlignment=NSTextAlignmentCenter;
}
else //else align textfield to left.
{
self.txt.textAlignment=NSTextAlignmentLeft;
}
return YES;
}
您可以通过将 attributedPlaceholder
与对齐设置为 .center
:
let centeredParagraphStyle = NSMutableParagraphStyle()
centeredParagraphStyle.alignment = .center
textField.attributedPlaceholder = NSAttributedString(
string: "Placeholder",
attributes: [.paragraphStyle: centeredParagraphStyle]
)
@Clay Ellis 的回答是正确的,这里是 Objective-C:
UITextField* field = [[UITextField alloc] initWithFrame: fieldRect];
NSTextAlignment alignment = NSTextAlignmentCenter;
NSMutableParagraphStyle* alignmentSetting = [[NSMutableParagraphStyle alloc] init];
alignmentSetting.alignment = alignment;
NSDictionary *attributes = @{NSParagraphStyleAttributeName : alignmentSetting};
NSAttributedString *str = [[NSAttributedString alloc] initWithString:placeholder attributes: attributes];
field.attributedPlaceholder = str;
based on Clay Ellis answer
详情
- Xcode 版本 10.2.1 (10E1001),Swift 5
解决方案 1
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
textField.attributedText = NSAttributedString(string: placeholder, attributes: [.paragraphStyle: paragraphStyle])
解决方案 2
import Foundation
extension String {
func toAttributed(alignment: NSTextAlignment) -> NSAttributedString {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
return toAttributed(attributes: [.paragraphStyle: paragraphStyle])
}
func toAttributed(attributes: [NSAttributedString.Key : Any]? = nil) -> NSAttributedString {
return NSAttributedString(string: self, attributes: attributes)
}
}
解决方案2的用法
// Way 1
textField.attributedPlaceholder = text.attributedString(alignment: .center)
// Way 2
textField.attributedPlaceholder = "title".attributedString(alignment: .center)
完整样本
Do not forget to add the solution code here
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let textField = UITextField()
textField.borderStyle = .roundedRect
view.addSubview(textField)
//textField.attributedPlaceholder = getAttributedString1()
textField.attributedPlaceholder = getAttributedString2()
textField.translatesAutoresizingMaskIntoConstraints = false
textField.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 24).isActive = true
textField.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 16).isActive = true
view.safeAreaLayoutGuide.rightAnchor.constraint(equalTo: textField.rightAnchor, constant: 16).isActive = true
}
private func getAttributedString1() -> NSAttributedString {
return "placeholder".toAttributed(alignment: .center)
}
private func getAttributedString2() -> NSAttributedString {
var attributes = [NSAttributedString.Key: Any]()
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
attributes[.paragraphStyle] = paragraphStyle
attributes[.font] = UIFont.systemFont(ofSize: 12, weight: .bold)
attributes[.foregroundColor] = UIColor.black.withAlphaComponent(0.5)
attributes[.underlineStyle] = NSUnderlineStyle.single.rawValue
attributes[.underlineColor] = UIColor.red
return "placeholder".toAttributed(attributes: attributes)
}
}
结果
@Clay Ellis 在 Swift 5
中的回答let centeredParagraphStyle = NSMutableParagraphStyle()
centeredParagraphStyle.alignment = .center
let attributedPlaceholder = NSAttributedString(string: "Placeholder", attributes: [NSAttributedString.Key.paragraphStyle: centeredParagraphStyle])
textField.attributedPlaceholder = attributedPlaceholder