if ([[UIDevice currentDevice] systemVersion].doubleValue >= 11.0) {
[[self.heightAnchor constraintEqualToConstant:44.0] setActive:YES];
} else {
[self setLeftPlaceholder];
}
- (void)setLeftPlaceholder {
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];
}
}
对于第三和第四个问题，用KVC获取textField，并对其进行定制。令textField位置、大小、圆角一致。
- (void)layoutSubviews{
[super layoutSubviews];
// search field
UITextField *searchField = [self valueForKey:@"searchField"];
searchField.backgroundColor = DARK_BLUE_COLOR;
searchField.textColor = [UIColor whiteColor];
searchField.font = [UIFont systemFontOfSize:16];
searchField.leftView = self.leftView;
searchField.frame = CGRectMake(0, 8, SCREEN_WIDTH, 28);
searchField.layer.cornerRadius = 5;
searchField.layer.masksToBounds = YES;
[searchField setValue:[UIColor whiteColor] forKeyPath:@"placeholderLabel.textColor"];
[self setValue:searchField forKey:@"searchField"];
self.searchTextPositionAdjustment = (UIOffset){10, 0}; // 光标偏移量
}
同样的，先看下运行效果
原本以为这下是没什么问题的，结果简直是坑
textFild的长度、位置、圆角都不一样 解释下这里出现的问题
观察上方图片上方的searchBar，会发现textField左边是圆角，右边是直角，说明是被截取的。导航栏titleView的范围就划分到了那个部分，而下边的searchBar连rightBarButton都不放过，直接抢占了位置。推测这是由于iOS 11导航栏视图层级变化产生的，可以这里了解下 www.jianshu.com/p/352f101d6… ，或者自行科普，不详细展开。所以对于searchBar的size设置要小心了，尽量控制在合适的范围。
textField的圆角是不一致的，自定义圆角大小时，取消其本身的圆角样式
searchField.borderStyle = UITextBorderStyleNone;
