为UITextField添加PlaceHolder支持
方法1（NSAttributedString）
NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:@"请输入不超过10个字的标题" attributes:
@{NSForegroundColorAttributeName:[UIColor colorWithHexString:@"999999"],
NSFontAttributeName:self.roomNameTf.font
}];
self.roomNameTf.attributedPlaceholder = attrString;
方法2（Category）
// UITextField+Placeholder.h
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@interface UITextField (Placeholder)
@property (nonatomic, strong) UIColor *placeholderColor;
@end
NS_ASSUME_NONNULL_END
// UITextField+Placeholder.m
#import "UITextField+Placeholder.h"
#import "LYHeader.h"
@implementation UITextField (Placeholder)
// 重写此方法 placeholder颜色
- (void)drawPlaceholderInRect:(CGRect)rect {
// 计算占位文字的 Size
CGSize placeholderSize = [self.placeholder sizeWithAttributes:
@{NSFontAttributeName : self.font}];
[self.placeholder drawInRect:CGRectMake(0, (rect.size.height - placeholderSize.height)/2, rect.size.width, rect.size.height) withAttributes:
@{NSForegroundColorAttributeName : [UIColor colorWithHexString:@"999999"],
NSFontAttributeName : self.font}];
}
- (UIColor *)placeholderColor{
return objc_getAssociatedObject(self, @selector(placeholderColor));
}
- (void)setPlaceholderColor:(UIColor *)placeholderColor{
objc_setAssociatedObject(self, @selector(placeholderColor), placeholderColor, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
@end
