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];
