UITextField von enterBackground zu enterForeground, Absturz der App

Question

benutzerdefiniertes UITextField: In der Click TextField Eingabe, Nach dem keyborad Popup, geben Sie den Hintergrund ein, um wieder in den Vordergrund zu kommen, Die App stürzt ab!

wenn Sie nicht TextField- Eingabe klicken, Hinter- oder Vordergrund Umwandlung, ist es normal, Teil des Codes:

@implementatio BKSearchViewController 
    - (void)setNavgationView { 
     BKSearchBar *searchBar = [[BKSearchBar alloc] initWithFrame:CGRectMake(20, 27, kScreenWidth - 90, 30)]; 
     searchBar.placeholder = @"输入昵称/拜托号"; 
     searchBar.delegate = self; 
     [searchBar setKeyboardType:UIKeyboardTypeDefault]; 
     [searchBar setReturnKeyType:UIReturnKeySearch]; 
     [searchBar setPlaceholderColor:kcallColor(@"a4a4a4")]; 
     [searchBar setPlaceholderFont:kFont(14)]; 
     [searchBar addTarget:self action:@selector(SearchTextFieldDidChange:) forControlEvents:UIControlEventEditingChanged]; 
     [navgationView addSubview:searchBar]; 
    } 
    @end 

    //BKSearchBar The key code 
       @implementation BKSearchBar 
       - (id)initWithFrame:(CGRect)frame 
       { 
        self = [super initWithFrame:frame]; 
        if (self) { 
         // 设置背景 
         self.backgroundColor = kcallColor(@"7d1d57"); 
         self.returnKeyType = UIReturnKeySearch; 
         // 设置内容 -- 垂直居中 
         self.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter; 
         [self UI]; 
        } 
        return self; 
       } 
    - (void)UI{ 
     // 设置左边显示一个放大镜 
     UIImageView *leftView = [[UIImageView alloc] init]; 
     omit... 
     //右边的view 
     UIImageView *rightView = [[UIImageView alloc] init]; 
     omit... 
    } 
      - (CGRect)placeholderRectForBounds:(CGRect)bounds{ 
       CGRect rect = CGRectMake(self.leftView.right, (self.height - 24)/2, bounds.size.width, 14); 
       return rect; 
      } 
      - (void)clearText{ 
       self.text = nil; 
      } 
      - (void)setPlaceholderColor:(UIColor *)color{ 
       [self setValue:color forKeyPath:@"_placeholderLabel.textColor"]; 
      } 
      - (void)setPlaceholderFont:(UIFont *)font{ 
       [self setValue:font forKeyPath:@"_placeholderLabel.font"]; 
      } 

Answer 1

danken all das Problem behoben ist wegen der Laufzeit

!!

+ (void)swizzleInstanceMethod:(Class)class originSelector:(SEL)originSelector otherSelector:(SEL)otherSelector 
{ 
    Method otherMehtod = class_getInstanceMethod(class, otherSelector); 
    Method originMehtod = class_getInstanceMethod(class, originSelector); 
    // 交换2个方法的实现 
    method_exchangeImplementations(otherMehtod, originMehtod); 
}