我知道shouldChangeTextInRange上的UITextFieldDelegate方法可以过滤UITextField上的输入，如果我只需要过滤一个UITextField就可以了。现在我的问题是我有很多需要过滤空格的UITextField。我不想在其中shouldChangeTextInRange的每个UIViewController上实施UITextField。无论如何都要扩展UITextField或其他吗？
答案 0 :(得分：1)
实际上这很简单，只是子类UITextField，添加委托给它，并在那里实现shouldChangeTextInRange。
class CustomTextField: UITextField, UITextFieldDelegate {
override func awakeFromNib() {
super.awakeFromNib()
delegate = self
}
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
if (string.rangeOfCharacterFromSet(.whitespaceCharacterSet()) != nil) {
return false
} else {
return true
}
}
}
答案 1 :(得分：0)
Swift允许扩展<!doctype html>
<head>
<meta name="description" content="Polymer iron-list items added while list hidden">
<meta charset="utf-8">
<base href="https://polygit.org/polymer+1.5.0/components/">
<script src="webcomponentsjs/webcomponents-lite.min.js"></script>
<link href="polymer/polymer.html" rel="import">
<link rel="import" href="iron-flex-layout/iron-flex-layout.html">
<link rel="import" href="iron-ajax/iron-ajax.html">
<link rel="import" href="paper-icon-button/paper-icon-button.html">
<link rel="import" href="iron-icon/iron-icon.html">
<link rel="import" href="iron-icons/iron-icons.html">
<link rel="import" href="paper-styles/color.html">
<link rel="import" href="paper-styles/typography.html">
<link rel="import" href="app-layout/app-toolbar/app-toolbar.html">
<link rel="import" href="paper-menu/paper-menu.html">
<link rel="import" href="paper-item/paper-item.html">
<link rel="import" href="paper-badge/paper-badge.html">
<link rel="import" href="iron-list/iron-list.html">
<style is="custom-style">
body {
@apply(--layout-fullbleed);
}
</style>
</head>
<body unresolved>
<x-app></x-app>
<dom-module id="x-app">
<style>
:host {
@apply(--layout-fit);
@apply(--layout-vertical);
@apply(--paper-font-common-base);
font-family: sans-serif;
}
app-toolbar {
background: var(--paper-pink-500);
box-shadow: 0 2px 5px 0 rgba(0, 0, 0, 0.3);
color: white;
z-index: 1;
color: white;
--paper-toolbar-title: {
font-size: 16px;
line-height: 16px;
font-weight: bold;
margin-left: 0;
}
;
}
app-toolbar paper-icon-button {
--paper-icon-button-ink-color: white;
}
#itemsList,
#selectedItemsList {
@apply(--layout-flex);
}
.item {
@apply(--layout-horizontal);
cursor: pointer;
padding: 16px 22px;
border-bottom: 1px solid #DDD;
}
.item:focus,
.item.selected:focus {
outline: 0;
background-color: #ddd;
}
.item.selected .star {
color: var(--paper-blue-600);
}
.item.selected {
background-color: var(--google-grey-300);
border-bottom: 1px solid #ccc;
}
.avatar {
height: 40px;
width: 40px;
border-radius: 20px;
box-sizing: border-box;
background-color: #ddd;
}
.pad {
@apply(--layout-flex);
@apply(--layout-vertical);
padding: 0 16px;
}
.primary {
font-size: 16px;
}
.secondary {
font-size: 14px;
}
.dim {
color: gray;
}
.star {
width: 24px;
height: 24px;
}
paper-badge {
-webkit-transition: all 0.1s;
transition: all 0.1s;
opacity: 1;
margin-top: 5px;
}
paper-badge[label="0"] {
opacity: 0;
}
#starredView {
width: 200px;
border-left: 1px solid #ddd;
}
paper-item {
white-space: nowrap;
cursor: pointer;
position: relative;
}
paper-item:hover::after {
content: "－";
width: 16px;
height: 16px;
display: block;
border-radius: 50% 50%;
background-color: var(--google-red-300);
margin-left: 10px;
line-height: 16px;
text-align: center;
color: white;
font-weight: bold;
text-decoration: none;
position: absolute;
right: 15px;
top: calc(50% - 8px);
}
.noSelection {
color: #999;
margin-left: 10px;
line-height: 50px;
}
.twoColumns {
@apply(--layout-flex);
@apply(--layout-horizontal);
overflow: hidden;
}
#starredView {
@apply(--layout-vertical);
}
</style>
<template>
<app-toolbar>
<div title>Selection using iron-list</div>
<div>
<paper-icon-button icon="icons:more-horiz" alt="hidden" on-tap="_toggleHidden"></paper-icon-button>
<paper-icon-button icon="icons:add" alt="add" on-tap="_changeContactList"></paper-icon-button>
<paper-badge label="[[selectedItems.length]]"></paper-badge>
</div>
</app-toolbar>
<!-- Main List for the items -->
<iron-list id="itemsList" items="[[data]]" selected-items="{{selectedItems}}" selection-enabled multi-selection hidden="{{hidden}}">
<template>
<div>
<div tabindex$="[[tabIndex]]" aria-label$="Select/Deselect [[item.name]]" class$="[[_computedClass(selected)]]">
<img class="avatar" src="[[item.image]]">
<div class="pad">
<div class="primary">
[[item.name]]
</div>
<div class="secondary dim">[[item.shortText]]</div>
</div>
<iron-icon icon="[[iconForItem(selected)]]" class="star"></iron-icon>
</div>
<div class="border"></div>
</div>
</template>
</iron-list>
</template>
<script>
HTMLImports.whenReady(function() {
Polymer({
is: "x-app",
behaviors: [
Polymer.IronResizableBehavior
],
listeners: {
'iron-resize': '_onIronResize'
},
properties: {
hidden: {
type: Object,
notify: true,
value: false,
observer: '_hiddenChanged'
},
selectedItems: {
type: Object
},
data: {
type: Object,
notify: true,
value: [{
"name": "Liz Grimes",
"image": "https://s3.amazonaws.com/uifaces/faces/twitter/enda/73.jpg",
"shortText": "est ad reprehenderit occaecat consequat"
}, {
"name": "Frazier Lara",
"image": "https://s3.amazonaws.com/uifaces/faces/twitter/guillogo/73.jpg",
"shortText": "consectetur culpa adipisicing voluptate enim"
}]
}
},
iconForItem: function(isSelected) {
return isSelected ? 'star' : 'star-border';
},
_computedClass: function(isSelected) {
var classes = 'item';
if (isSelected) {
classes += ' selected';
}
return classes;
},
_hiddenChanged: function(hidden) {
if (!hidden) {
console.log('firing iron-list.iron-resize');
this.$.itemsList.fire('iron-resize');
}
},
_unselect: function(e) {
this.$.itemsList.deselectItem(e.model.item);
},
_changeContactList: function() {
this.push('data', {
"name": "Shelley Molina",
"image": "https://s3.amazonaws.com/uifaces/faces/twitter/smalonso/73.jpg",
"shortText": "laboris do velit ipsum non"
});
console.log('Replace data !')
},
_toggleHidden: function() {
this.hidden = !this.hidden;
console.log('Hidden : ' + this.hidden)
},
_onIronResize: function() {
console.log('Resize');
}
});
});
</script>
</dom-module>
</body>。您可以创建protocols并在该方法中实现自定义代码。但是有一些限制，请查看此答案，它会对您有所帮助swift 2.0 - UITextFieldDelegate protocol extension not working