Hacky way 解决 iOS 7 UISearchBar 默认文本居左展示问题

浏览数：194 / 时间：2015年06月11日

参考：ON IOS 7 UISEARCHBAR LEFT ALIGN PLACEHOLDER TEXT?

控件代码：https://gist.github.com/CoCrash/de56f5f0b70b7eb6d6e3

一个私有方法setCenterPlaceholder，在调用时修改这个布尔值可以实现修改位置的效果。

1 @interface NSCodingSearchBar : UISearchBar
2  
3 // Default by the system is YES.
4 // https://github.com/nst/iOS-Runtime-Headers/blob/master/Frameworks/UIKit.framework/UISearchBar.h
5 @property (nonatomic, assign, setter = setHasCentredPlaceholder:) BOOL hasCentredPlaceholder;
6  
7 @end

实现文件：

 1 @implementation NSCodingSearchBar
 2  
 3  
 4 // ------------------------------------------------------------------------------------------
 5 #pragma mark - Initializers
 6 // ------------------------------------------------------------------------------------------
 7 - (instancetype)initWithFrame:(CGRect)frame
 8 {
 9     if ((self = [super initWithFrame:frame]))
10     {
11         self.hasCentredPlaceholder = YES;
12     }
13     
14     return self;
15 }
16  
17  
18 // ------------------------------------------------------------------------------------------
19 #pragma mark - Methods
20 // ------------------------------------------------------------------------------------------
21 - (void)setHasCentredPlaceholder:(BOOL)hasCentredPlaceholder
22 {
23     _hasCentredPlaceholder = hasCentredPlaceholder;
24     
25     SEL centerSelector = NSSelectorFromString([NSString stringWithFormat:@"%@%@", @"setCenter", @"Placeholder:"]);
26     if ([self respondsToSelector:centerSelector])
27     {
28         NSMethodSignature *signature = [[UISearchBar class] instanceMethodSignatureForSelector:centerSelector];
29         NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
30         [invocation setTarget:self];
31         [invocation setSelector:centerSelector];
32         [invocation setArgument:&_hasCentredPlaceholder atIndex:2];
33         [invocation invoke];
34     }
35     
36 }
37  
38  
39 @end