在iOS 7上UISearchBar左对齐占位符文本？

Question

在iOS 7 UISearchBar上,占位符文本居中,我想禁用它并使它始终像以前一样粘在左边.

在diffs上有一个私有方法setCenterPlaceholder,并且用BOOL调用它会使之旅行.https://gist.github.com/nscoding/7220368

头文件

@interface NSCodingSearchBar : UISearchBar

// Default by the system is YES.
// https://github.com/nst/iOS-Runtime-Headers/blob/master/Frameworks/UIKit.framework/UISearchBar.h
@property (nonatomic, assign, setter = setHasCentredPlaceholder:) BOOL hasCentredPlaceholder;

@end

实施文件

#import "NSCodingSearchBar.h"


// ------------------------------------------------------------------------------------------


@implementation NSCodingSearchBar


// ------------------------------------------------------------------------------------------
#pragma mark - Initializers
// ------------------------------------------------------------------------------------------
- (instancetype)initWithFrame:(CGRect)frame
{
    if ((self = [super initWithFrame:frame]))
    {
        self.hasCentredPlaceholder = YES;
    }

    return self;
}


// ------------------------------------------------------------------------------------------
#pragma mark - Methods
// ------------------------------------------------------------------------------------------
- (void)setHasCentredPlaceholder:(BOOL)hasCentredPlaceholder
{
    _hasCentredPlaceholder = hasCentredPlaceholder;

    SEL centerSelector = NSSelectorFromString([NSString stringWithFormat:@"%@%@", @"setCenter", @"Placeholder:"]);
    if ([self respondsToSelector:centerSelector])
    {
        NSMethodSignature *signature = [[UISearchBar class] instanceMethodSignatureForSelector:centerSelector];
        NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
        [invocation setTarget:self];
        [invocation setSelector:centerSelector];
        [invocation setArgument:&_hasCentredPlaceholder atIndex:2];
        [invocation invoke];
    }

}


@end

我想知道是否有任何其他的,而不是"Hacky方式"做同样的事情.

Answer 1

我还没有尝试过，UISearchBar但这适用于 a UITextField。我对它进行了子类化并覆盖了leftViewRectForBounds:, textRectForBounds:and editingRectForBounds:，这是代码：

- (CGRect)textRectForBounds:(CGRect)bounds {
  CGRect inset = CGRectMake(bounds.origin.x + kLeftTextPadding,
                        bounds.origin.y,
                        bounds.size.width - kLeftTextPadding,
                        bounds.size.height);
  return inset;
}

希望能帮助到你。