iOS開發封裝篇-利用KVC修改UITextField的placeholderLabel顏色

大大小小也做了好幾個項目了，系統原生的控件越來越不能滿足開發（其實是產品經理）的需求了，接下來打算把開發中常用的控件封裝一下。剛好今天產品經理要求改一下UITextField的佔位文字的顏色，於是就打算搞一下。在思考怎麼滿足產品經理需求的時候，想到了三個方案，

一是利用富文本，可以很隨意的修改placeholderLabel顏色和字體大小。具體代碼如下：

    NSMutableAttributedString *placehoder = [[NSMutableAttributedString alloc] initWithString:@"手機號"];
    [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;

效果圖如下：

二是重繪，- (void)drawPlaceholderInRect:(CGRect)rect方法裏重新畫圖：這個就不上效果圖了。

#import "WDDTextField.h"

@implementation WDDTextField

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

@end

三是利用KVC修改placeholderLabel的顏色以及字體大小：

static NSString * const WDDPlaceholderColorkeyPath = @"_placeholderLabel.textColor";
static NSString * const WDDPlaceholderFontPath = @"_placeholderLabel.font";

@implementation WDDTextField

-(instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {
        [self awakeFromNib];
    }
    return self;
}
- (void)awakeFromNib
{
    // 設置光標顏色和文字顏色一致
    self.tintColor = self.textColor;
    // 不成爲第一響應者
    [self resignFirstResponder];
}

/**
* 當前文本框聚焦時就會調用
*/
- (BOOL)becomeFirstResponder
{
    // 修改佔位文字字體大小
    if (self.placeholderHighlightedFont) {
        [self setValue:self.placeholderHighlightedFont forKeyPath:WDDPlaceholderFontPath];

    }else
    {
        [self setValue:self.font forKeyPath:WDDPlaceholderFontPath];
    }

    // 修改佔位文字顏色
    if (self.placeholderHighlightedColor) {
        [self setValue:self.placeholderHighlightedColor forKeyPath:WDDPlaceholderColorkeyPath];
    }else
    {
        [self setValue:self.textColor forKeyPath:WDDPlaceholderColorkeyPath];
    }
    return [super becomeFirstResponder];
}

/**
* 當前文本框失去焦點時就會調用
*/
- (BOOL)resignFirstResponder
{
    // 修改佔位文字字體大小
    if (self.placeholderNormalFont) {
        [self setValue:self.placeholderNormalFont forKeyPath:WDDPlaceholderFontPath];
    }else
    {
        [self setValue:self.font forKeyPath:WDDPlaceholderFontPath];
    }

    // 修改佔位文字顏色
    if (self.placeholderNormalColor) {
        [self setValue:self.placeholderNormalColor forKeyPath:WDDPlaceholderColorkeyPath];
    }else
    {
        [self setValue:self.textColor forKeyPath:WDDPlaceholderColorkeyPath];
    }
    return [super resignFirstResponder];
}