UITextField的使用

修改UITextField的光标颜色

textField.tintColor = [UIColor whiteColor];

UITextField占位文字相关的设置

// 设置占位文字内容 @property(nullable, nonatomic,copy) NSString *placeholder; // 设置带有属性的占位文字, 优先级 > placeholder @property(nullable, nonatomic,copy) NSAttributedString *attributedPlaceholder;

NSAttributedString

带有属性的字符串, 富文本

由2部分组成

- 文字内容 : NSString * - 文字属性 : NSDictionary * - 文字颜色 - NSForegroundColorAttributeName - 字体大小 - NSFontAttributeName - 下划线 - NSUnderlineStyleAttributeName - 背景色 - NSBackgroundColorAttributeName

初始化

NSMutableDictionary *attributes = [NSMutableDictionary dictionary]; attributes[NSForegroundColorAttributeName] = [UIColor yellowColor]; attributes[NSBackgroundColorAttributeName] = [UIColor redColor]; attributes[NSUnderlineStyleAttributeName] = @YES; NSAttributedString *string = [[NSAttributedString alloc] initWithString:@"123" attributes:attributes];

使用场合

- UILabel - attributedText - UITextField - attributedPlaceholder

NSMutableAttributedString

继承自NSAttributedString

常见方法

// 设置range范围的属性, 重复设置同一个范围的属性, 最后一次设置才是有效的(之前的设置会被覆盖掉) //- (void)setAttributes:(nullable NSDictionary<NSString *, id> *)attrs range:(NSRange)range; // 添加range范围的属性, 同一个范围, 可以不断累加属性 //- (void)addAttribute:(NSString *)name value:(id)value range:(NSRange)range; //- (void)addAttributes:(NSDictionary<NSString *, id> *)attrs range:(NSRange)range;

图文混排

UILabel *label = [[UILabel alloc] init]; label.frame = CGRectMake(100, 100, 200, 25); label.backgroundColor = [UIColor redColor]; label.font = [UIFont systemFontOfSize:14]; [self.view addSubview:label]; // 图文混排 NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] init]; // 1 - 你好 NSAttributedString *first = [[NSAttributedString alloc] initWithString:@"你好"]; [attributedText appendAttributedString:first]; // 2 - 图片 // 带有图片的附件对象 NSTextAttachment *attachment = [[NSTextAttachment alloc] init]; attachment.image = [UIImage imageNamed:@"header_cry_icon"]; CGFloat lineH = label.font.lineHeight; attachment.bounds = CGRectMake(0, - ((label.xmg_height - lineH) * 0.5 - 1), lineH, lineH); // 将附件对象包装成一个属性文字 NSAttributedString *second = [NSAttributedString attributedStringWithAttachment:attachment]; [attributedText appendAttributedString:second]; // 3 - 哈哈哈 NSAttributedString *third = [[NSAttributedString alloc] initWithString:@"哈哈哈"]; [attributedText appendAttributedString:third]; label.attributedText = attributedText;

一个Label显示多行不同字体的文字

UILabel *label = [[UILabel alloc] init]; // 设置属性文字 NSString *text = @"你好\n哈哈哈"; NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:text]; [attributedText addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:10] range:NSMakeRange(0, text.length)]; [attributedText addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:13] range:NSMakeRange(3, 3)]; label.attributedText = attributedText; // 其他设置 label.numberOfLines = 0; label.textAlignment = NSTextAlignmentCenter; label.frame = CGRectMake(0, 0, 100, 40); [self.view addSubview:label]; self.navigationItem.titleView = label;

修改UITextField占位文字的颜色

使用attributedPlaceholder

@property(nullable, nonatomic,copy) NSAttributedString *attributedPlaceholder; 重写- (void)drawPlaceholderInRect:(CGRect)rect; - (void)drawPlaceholderInRect:(CGRect)rect;

修改内部占位文字Label的文字颜色

[textField setValue:[UIColor grayColor] forKeyPath:@"placeholderLabel.textColor"];

如何监听一个控件内部的事件

如果继承自UIControl

- (void)addTarget:(nullable id)target action:(SEL)action forControlEvents:(UIControlEvents)controlEvents;

代理

通知

利用内部的某些机制

比如重写UITextField的becomeFirstResponder和resignFirstResponder来监听UITextField的获得焦点和失去焦点事件

assign和weak的区别

本质区别

速度比较: __unsafe_unretained > __weak

@property (nonatomic, assign) WDDog *dog; // WDDog *__unsafe_unretained _dog;

__unsafe_unretained的特点: 1.不是强引用, 不能保住OC对象的命 2.如果引用的OC对象销毁了, 指针并不会被自动清空, 依然指向销毁的对象(很容易产生野指针错误: EXC_BAD_ACCESS)

@property (nonatomic, weak) WDDog *dog; // WDDog * _Nullable __weak _dog;

__weak的特点: 1.不是强引用, 不能保住OC对象的命 2.如果引用的OC对象销毁了, 指针会被自动清空(变为nil), 不再指向销毁的对象(永远不会产生野指针错误)

用途 assign一般用在基本数据类型上面, 比如int\double等weak一般用在代理对象上面, 或者用来解决循环强引用的问题

监听UITextField的获得焦点和失去焦点事件

addTarget

[textField addTarget:target action:@selector(editingDidBegin) forControlEvents:UIControlEventEditingDidBegin]; [textField addTarget:target action:@selector(editingDidEnd) forControlEvents:UIControlEventEditingDidEnd]; UIControlEventEditingDidBegin 1.开始编辑 2.获得焦点 3.弹出键盘 UIControlEventEditingDidEnd 1.结束编辑 2.失去焦点 3.退下键盘

delegate

textField.delegate = self; #pragma mark - <UITextFieldDelegate> - (void)textFieldDidBeginEditing:(UITextField *)textField { } - (void)textFieldDidEndEditing:(UITextField *)textField { }

通知

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(beginEditing) name:UITextFieldTextDidBeginEditingNotification object:textField]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(endEditing) name:UITextFieldTextDidEndEditingNotification object:textField]; - (void)dealloc { [[NSNotificationCenter defaultCenter] removeObserver:self]; } - (void)beginEditing { } - (void)endEditing { } - 重写UITextField的`becomeFirstResponder`和`resignFirstResponder`方法 /** * 调用时刻 : 成为第一响应者(开始编辑\弹出键盘\获得焦点) */ - (BOOL)becomeFirstResponder { return [super becomeFirstResponder]; } /** * 调用时刻 : 不做第一响应者(结束编辑\退出键盘\失去焦点) */ - (BOOL)resignFirstResponder { return [super resignFirstResponder]; }