重写TextField

       我们有时需要定制化UITextField对象的风格，可以添加许多不同的重写方法，来改变文本字段的显示行为。这些方法都会返回一个CGRect结构，制定了文本字段每个部件的边界范围，甚至修改placeHolder颜色，字体。

– textRectForBounds://重写来重置文字区域

–drawTextInRect://改变绘文字属性.重写时调用super可以按默认图形属性绘制,若自己完全重写绘制函数，就不用调用super了.

– placeholderRectForBounds://重写来重置占位符区域

–drawPlaceholderInRect://重写改变绘制占位符属性.重写时调用super可以按默认图形属性绘制,若自己完全重写绘制函数，就不用调用super了

– borderRectForBounds://重写来重置边缘区域

– editingRectForBounds://重写来重置编辑区域

– clearButtonRectForBounds://重写来重置clearButton位置,改变size可能导致button的图片失真

– leftViewRectForBounds:

– rightViewRectForBounds:

通过– drawPlaceholderInRect:方法可改变placeHolder颜色、字体，请看代码：

首先定义一个类CustomTextField让它继承UITextField实现以下方法即可：

//控制清除按钮的位置

-(CGRect)clearButtonRectForBounds:(CGRect)bounds{

returnCGRectMake(bounds.origin.x+bounds.size.width-50,bounds.origin.y+bounds.size.height-20,16,16);

}

//控制placeHolder的位置，左右缩20

-(CGRect)placeholderRectForBounds:(CGRect)bounds{

//return CGRectInset(bounds,20, 0);

CGRectinset=CGRectMake(bounds.origin.x+100, bounds.origin.y, bounds.size.width-10, bounds.size.height);//更好理解些

returninset;

}

//控制显示文本的位置

-(CGRect)textRectForBounds:(CGRect)bounds{

//returnCGRectInset(bounds, 50, 0);

CGRectinset=CGRectMake(bounds.origin.x+190, bounds.origin.y, bounds.size.width-10, bounds.size.height);//更好理解些

returninset;

}

//控制编辑文本的位置

-(CGRect)editingRectForBounds:(CGRect)bounds{

//return CGRectInset(bounds, 10 , 0 );

CGRectinset=CGRectMake(bounds.origin.x+10, bounds.origin.y, bounds.size.width-10, bounds.size.height);

returninset;

}

//控制左视图位置

- (CGRect)leftViewRectForBounds:(CGRect)bounds{

CGRectinset=CGRectMake(bounds.origin.x+10, bounds.origin.y, bounds.size.width-250, bounds.size.height);

returninset;

//returnCGRectInset(bounds,50,0);

}

//控制placeHolder的颜色、字体

- (void)drawPlaceholderInRect:(CGRect)rect{

//CGContextRef context =UIGraphicsGetCurrentContext();

//CGContextSetFillColorWithColor(context,[UIColor yellowColor].CGColor);

[[UIColororangeColor]setFill];

[[selfplaceholder]drawInRect:rectwithFont:[UIFontsystemFontOfSize:20]];

}

//下面是使用CustomTextField的代码，可放在viewDidLoad等方法中

_textField= [[CustomTextFieldalloc]initWithFrame:CGRectMake(20,150,280,30)];

_textField.placeholder=@"请输入帐号信息";

_textField.borderStyle=UITextBorderStyleRoundedRect;

_textField.textAlignment=UITextAlignmentLeft;

_textField.delegate=self;

_textField.clearButtonMode=UITextFieldViewModeWhileEditing;

_textField.text=@"aa";

UIImageView*imgv =[[UIImageViewalloc]initWithImage:[UIImageimageNamed:@"icon-iwant-2.png"]];

_textField.leftView=imgv;

_textField.leftViewMode=UITextFieldViewModeAlways;

[self.viewaddSubview:_textField];