### 自定义控件 - textfield 带动画

@interface YCAnimationTextField : UIView
//注释文字正常情况颜色
@property (nonatomic, strong) UIColor *placeHolderNormalTextColor;
//注释文字选中情况颜色
@property (nonatomic, strong) UIColor *placeHolderSelectTextColor;
//光标颜色
@property (nonatomic, strong) UIColor *cursorColor;
//注释文字
@property (nonatomic, copy) NSString *placeHolder;
@end

#import "YCAnimationTextField.h"

#define kSelfWidth CGRectGetWidth(self.frame)
#define kSelfHeight CGRectGetHeight(self.frame)
const CGFloat lineWidth = 1.f;
const CGFloat duration = .2f;

@interface YCAnimationTextField ()
@property (nonatomic, strong) UILabel *placeHolderLb;
@property (nonatomic, strong) UITextField *textField;
@property (nonatomic, strong) UIView *bottomLine;
@property (nonatomic, strong) CALayer *bottomLayer;

@property (nonatomic, assign) BOOL moved;
@end
@implementation YCAnimationTextField

@synthesize placeHolderNormalTextColor = _placeHolderNormalTextColor;

- (instancetype)initWithFrame:(CGRect)frame{
    if (self = [super initWithFrame:frame]) {
        
        _placeHolderLb = [UILabel new];
        _placeHolderLb.font = [UIFont systemFontOfSize:15];
        _placeHolderLb.textColor = self.placeHolderNormalTextColor;
        [self addSubview:_placeHolderLb];
        
        _textField = [UITextField new];
        _textField.backgroundColor = [UIColor clearColor];
        _textField.textColor = [UIColor whiteColor];
        _textField.font = [UIFont systemFontOfSize:15];
        //光标颜色
        _textField.tintColor = [UIColor whiteColor];
        _textField.borderStyle = UITextBorderStyleNone;
        [self addSubview:_textField];
        
        _bottomLine = [UIView new];
        _bottomLine.backgroundColor = [UIColor lightGrayColor];
        [self addSubview:_bottomLine];
        
        _bottomLayer = [CALayer layer];
        _bottomLayer.backgroundColor = [UIColor whiteColor].CGColor;
        _bottomLayer.anchorPoint = CGPointMake(0, 0.5);
        _bottomLayer.frame = CGRectMake(0, 0, 0, lineWidth);
        //直接添加到_bottomLine.layer中,不要添加到self.layer
        [_bottomLine.layer addSublayer:_bottomLayer];
        
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(valueDidChanged:) name:UITextFieldTextDidChangeNotification object:_textField];
    }
    return self;
}

- (void)layoutSubviews{
    [super layoutSubviews];
    _placeHolderLb.frame = CGRectMake(0, 0, kSelfWidth, kSelfHeight-lineWidth);
    _bottomLine.frame = CGRectMake(0, kSelfHeight-lineWidth, kSelfWidth, lineWidth);
    _textField.frame = CGRectMake(0, 0, kSelfWidth, kSelfHeight-lineWidth);
}

- (void)valueDidChanged:(NSNotification *)notify{
    [self placeHolderFrameChange];
}

- (void)placeHolderFrameChange{
    CGFloat x = _placeHolderLb.center.x;
    CGFloat y = _placeHolderLb.center.y;
    
    if (_textField.text.length>0 && !_moved) {
        [self moveAnimationWithX:x andY:y];
    }else if (_textField.text.length == 0 && _moved){
        [self backAnimationWithX:x andY:y];
    }
}

- (void)moveAnimationWithX:(CGFloat)x andY:(CGFloat)y{
    _moved = YES;
    
    _placeHolderLb.textColor = _placeHolderSelectTextColor;
    x -= 2;
    y -= _placeHolderLb.frame.size.height/2-3;
    [UIView animateWithDuration:duration animations:^{
        _placeHolderLb.font = [UIFont systemFontOfSize:11];
        _bottomLayer.frame = CGRectMake(0, 0, kSelfWidth, lineWidth);
        _placeHolderLb.center = CGPointMake(x, y);
        _placeHolderLb.alpha =1;
    }];
}

- (void)backAnimationWithX:(CGFloat)x andY:(CGFloat)y{
    _moved = NO;
    
    _placeHolderLb.textColor = self.placeHolderNormalTextColor;
    x += 2;
    y += _placeHolderLb.frame.size.height/2-3;
    [UIView animateWithDuration:duration animations:^{
        _placeHolderLb.font = [UIFont systemFontOfSize:15];
        _bottomLayer.frame = CGRectMake(0, 0, 0, lineWidth);
        _placeHolderLb.center = CGPointMake(x, y);
        _placeHolderLb.alpha =1;
    }];
}

- (void)setPlaceHolder:(NSString *)placeHolder{
    _placeHolder = placeHolder;
    _placeHolderLb.text = placeHolder;
}

- (void)setPlaceHolderNormalTextColor:(UIColor *)placeHolderNormalTextColor{
    _placeHolderNormalTextColor = placeHolderNormalTextColor;
    _placeHolderLb.textColor = placeHolderNormalTextColor;
}

- (UIColor *)placeHolderSelectTextColor{
    if (!_placeHolderSelectTextColor) {
        return [UIColor blackColor];
    }else{
        return _placeHolderSelectTextColor;
    }
}

- (UIColor *)placeHolderNormalTextColor{
    if (!_placeHolderNormalTextColor) {
        return [UIColor blackColor];
    }else{
        return _placeHolderNormalTextColor;
    }
}

- (void)setCursorColor:(UIColor *)cursorColor{
    _cursorColor = cursorColor;
    _textField.tintColor = cursorColor;
}
@end