0.备注:
本文是参考网上其他文章写的,权作学习记录.
1.新建一个 UISearchBar 的分类
UISearchBar+DJSearchBarPlaceholder
2.代码部分
.h 文件内:
#import <UIKit/UIKit.h>
@interface UISearchBar (DJSearchBarPlaceholder)
-(void)changePlaceholderToLeft:(NSString *)placeholder;
@end
.m 文件内:
#import "UISearchBar+DJSearchBarPlaceholder.h"
@implementation UISearchBar (DJSearchBarPlaceholder)
-(void)changePlaceholderToLeft:(NSString *)placeholder {
self.placeholder = placeholder;
SEL centerSelector = NSSelectorFromString([NSString stringWithFormat:@"%@%@", @"setCenter", @"Placeholder:"]);
if ([self respondsToSelector:centerSelector]) {
BOOL centeredPlaceholder = NO;
NSMethodSignature *signature = [[UISearchBar class] instanceMethodSignatureForSelector:centerSelector];
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
[invocation setTarget:self];
[invocation setSelector:centerSelector];
[invocation setArgument:¢eredPlaceholder atIndex:2];
[invocation invoke];
}
}
@end
3.使用
初始化 UISearchBar 对象并调用分类里的对象方法设置 placeholder 即可.
