设置UILabel和UITextField的Insets

Insets这个名字有点让人费解，其实它表示的是内容与控件边界的距离，相当于CSS中的padding。

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目前，在iOS的控件中，只看到UIButton可以设置Insets，对应的属性是：contentEdgeInsets、titleEdgeInsets、imageEdgeInsets，它们接受的属性类型都是UIEdgeInsets，可以由函数UIEdgeInsetsMake(CGFloat top, CGFloat left, CGFloat bottom, CGFloat right)构造。在xib中也有界面来对按钮的这三个EdgeInsets属性进行设置，分别是按钮的Edge和 Inset属性。

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如果想设置UILable或UITextField中的文本离边界的距离，无伦是在xib里还是直接代码的方式都无能为力，因为苹果未开放相应的属性让你去控制，所以，我们只能自定义相应的控件。

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首先来看看UILabel的子类InsetsLabel的实现代码。

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#import <UIKit/UIKit.h>@interface InsetsLabel : UILabel@property(nonatomic) UIEdgeInsets insets;- (id)initWithFrame:(CGRect)frame andInsets:(UIEdgeInsets) insets;- (id)initWithInsets:(UIEdgeInsets) insets;@end

#import "InsetsLabel.h"@implementation InsetsLabel@synthesize insets = _insets;- (id)initWithFrame:(CGRect)frame andInsets:(UIEdgeInsets)insets { self = [super initWithFrame:frame]; if(self) { self.insets = insets; } return self;}- (id)initWithInsets:(UIEdgeInsets)insets { self = [super init]; if(self) { self.insets = insets; } return self;}- (void)drawTextInRect:(CGRect)rect { return [super drawTextInRect:UIEdgeInsetsInsetRect(rect, self.insets)];}@end

#import <UIKit/UIKit.h>@interface InsetsTextField : UITextField@end

#import "InsetsTextField.h"@implementation InsetsTextField//控制placeHolder的位置- (CGRect)textRectForBounds:(CGRect)bounds { return CGRectInset(bounds, 20, 0);}//控制文本的位置- (CGRect)editingRectForBounds:(CGRect)bounds { return CGRectInset(bounds, 20, 0);}@end

UITextField *textField = [[UITextField alloc] init];UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 10, 25)];label.text = @"$";label.textColor = [UIColor darkGrayColor];label.backgroundColor = [UIColor clearColor];textField.frame = CGRectMake(0, 0, 180, 25);textField.borderStyle = UITextBorderStyleRoundedRect;textField.leftView = label;textField.leftViewMode = UITextFieldViewModeAlways;[self.view addSubview:textField];[label release];[textField release];