修改UITextField的placeholder颜色

冷不防 2022-07-29 11:52 230阅读 0赞

## 修改UITextField的placeholder颜色 ##

*  使用属性

@property(nonatomic,copy)   NSAttributedString     *attributedPlaceholder;
    
    // 文字属性
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];
    
    // NSAttributedString : 带有属性的文字(富文本技术)
    NSAttributedString *placeholder = [[NSAttributedString alloc] initWithString:@"手机号" attributes:attrs];
    self.phoneField.attributedPlaceholder = placeholder;
    
    NSMutableAttributedString *placehoder = [[NSMutableAttributedString alloc] initWithString:@"手机号"];
    [placehoder setAttributes:@{NSForegroundColorAttributeName : [UIColor whiteColor]} range:NSMakeRange(0, 1)];
    [placehoder setAttributes:@{
                                NSForegroundColorAttributeName : [UIColor yellowColor],
                                NSFontAttributeName : [UIFont systemFontOfSize:30]
                                } range:NSMakeRange(1, 1)];
    [placehoder setAttributes:@{NSForegroundColorAttributeName : [UIColor redColor]} range:NSMakeRange(2, 1)];
    self.phoneField.attributedPlaceholder = placehoder;

*  重写方法

- (void)drawPlaceholderInRect:(CGRect)rect
    {
        [self.placeholder drawInRect:CGRectMake(0, 10, rect.size.width, 25) withAttributes:@{
                                                           NSForegroundColorAttributeName : [UIColor grayColor],
                                                           NSFontAttributeName : self.font}];
    }

*  使用KVC

[self setValue:[UIColor grayColor] forKeyPath:@"_placeholderLabel.textColor"];

## 运行时(Runtime) ##

*  苹果官方一套C语言库
 *  能做很多底层操作(比如访问隐藏的一些成员变量\\成员方法….)
 *  访问成员变量举例

unsigned int count = 0;
    
    // 拷贝出所有的成员变量列表
    Ivar *ivars = class_copyIvarList([UITextField class], &count);
    
    for (int i = 0; i<count; i++) {
        // 取出成员变量
        // Ivar ivar = *(ivars + i);
        Ivar ivar = ivars[i];
    
        // 打印成员变量名字
        XMGLog(@"%s", ivar_getName(ivar));
    }
    
    // 释放
    free(ivars);

![这里写图片描述][20160416230727349]

[20160416230727349]: /images/20220724/4d62b377019149acb1e85047ad72463f.png