做登录页面,之前做都是用frame做,今天想着用Auto Layout中的VFL来做。觉得做的效果还是可以的(自恋一下下)。
首先看下效果图和标记图
自己在做的过程中也遇到了好多问题,不过也一个一个的自己解决了
1.子视图居中的问题
上一博客我也写了,由于指定了视图的宽度高度,想让视图居中对齐,可它就是不能达到预期,最后还是网上找了下才解决的。
2.约束不起作用
引起这个问题的原因很多,其中有一个是犯的最愚蠢的错误,就是添加约束前设置子视图
setTranslatesAutoresizingMaskIntoConstraintsNO.
setTranslatesAutoresizingMaskIntoConstraints=NO.
setTranslatesAutoresizingMaskIntoConstraints=NO
重要的事情说三遍
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上面说的适配,这里说下实现
根据上图有一个账号 一个密码,它们两个只是图片 名称和文本类型不一样其他都一样,所以我就把它封装成一个View。
// // LoginView.h // Login // // Created by City--Online on 15/9/8. // Copyright (c) 2015年 City--Online. All rights reserved. // #import <UIKit/UIKit.h>@interface LoginView : UIView @property (nonatomic,strong) UIImageView *leftImgView; @property (nonatomic,strong) UILabel *nameLabel; @property (nonatomic,strong) UITextField *txtField; @property (nonatomic,strong) UIView *bottomLine; @end
// // LoginView.m // Login // // Created by City--Online on 15/9/8. // Copyright (c) 2015年 City--Online. All rights reserved. // #import "LoginView.h"@implementation LoginView -(instancetype)init {self=[super init];if (self) {[self setTranslatesAutoresizingMaskIntoConstraints:NO];//左边图片_leftImgView=[[UIImageView alloc]init];[_leftImgView setTranslatesAutoresizingMaskIntoConstraints:NO];[self addSubview:_leftImgView];//名称_nameLabel=[[UILabel alloc]init];_nameLabel.font=[UIFont systemFontOfSize:18.0];_nameLabel.textColor=[UIColor colorWithRed:0.200f green:0.200f blue:0.200f alpha:1.00f];[_nameLabel setTranslatesAutoresizingMaskIntoConstraints:NO];[self addSubview:_nameLabel];//输入文本框_txtField=[[UITextField alloc]init];_txtField.font=[UIFont systemFontOfSize:18]; // _txtField.layer.borderWidth=2.0; [_txtField setTranslatesAutoresizingMaskIntoConstraints:NO];[self addSubview:_txtField];//底部线条_bottomLine=[[UIView alloc]init];_bottomLine.backgroundColor=[UIColor colorWithRed:0.427f green:0.427f blue:0.427f alpha:1.00f];[_bottomLine setTranslatesAutoresizingMaskIntoConstraints:NO];[self addSubview:_bottomLine];}return self; } -(void)updateConstraints {[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-35-[_leftImgView(25)]-10-[_nameLabel(40)]-5-[_txtField]-35-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_leftImgView,_nameLabel,_txtField)]];[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-30-[_leftImgView(25)]-10-[_bottomLine(0.5)]-0-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_leftImgView,_bottomLine)]];[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-30-[_bottomLine]-30-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_bottomLine)]];[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-25-[_txtField]-5-[_bottomLine(0.5)]-0-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_txtField,_bottomLine)]];[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[_nameLabel]-0-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_nameLabel)]];[super updateConstraints]; }@end
在界面中布局登录页面:
// // ViewController.m // Login // // Created by City--Online on 15/9/8. // Copyright (c) 2015年 City--Online. All rights reserved. // #import "ViewController.h" #import "LoginView.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {[super viewDidLoad];self.view.backgroundColor=[UIColor whiteColor];//顶部图片UIImageView *headView=[[UIImageView alloc]initWithImage:[UIImage imageNamed:@"MR WU.png"]];[headView setTranslatesAutoresizingMaskIntoConstraints:NO];[self.view addSubview:headView];NSDictionary* views = NSDictionaryOfVariableBindings(headView);//设置高度[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-90-[headView(100)]" options:0 metrics:nil views:views]];//设置宽度[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"[headView(100)]" options:0 metrics:nil views:views]];//水平居中[self.view addConstraint:[NSLayoutConstraint constraintWithItem:headView attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1 constant:0]];//账号LoginView *accountView=[[LoginView alloc]init];accountView.leftImgView.image=[UIImage imageNamed:@"user.png"];accountView.nameLabel.text=@"账号";accountView.txtField.secureTextEntry=NO;[self.view addSubview:accountView];[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[accountView]-0-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(accountView)]];[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[headView]-50-[accountView(66)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(headView,accountView)]];//密码LoginView *passWordView=[[LoginView alloc]init];passWordView.leftImgView.image=[UIImage imageNamed:@"lock-"];passWordView.nameLabel.text=@"密码";passWordView.txtField.secureTextEntry=YES;[self.view addSubview:passWordView];[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[passWordView]-0-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(passWordView)]];[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[accountView]-0-[passWordView(accountView)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(accountView,passWordView)]];//登录按钮UIButton *loginBtn=[UIButton buttonWithType:UIButtonTypeRoundedRect];[loginBtn setTranslatesAutoresizingMaskIntoConstraints:NO];[loginBtn setTitle:@"登录" forState:UIControlStateNormal];[loginBtn setTitleColor:[UIColor colorWithRed:1.000f green:1.000f blue:1.000f alpha:1.00f] forState:UIControlStateNormal];loginBtn.titleLabel.font=[UIFont systemFontOfSize:20];loginBtn.backgroundColor=[UIColor colorWithRed:0.992f green:0.318f blue:0.106f alpha:1.00f];[self.view addSubview:loginBtn];[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[passWordView]-25-[loginBtn(45)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(passWordView,loginBtn)]];[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-30-[loginBtn]-30-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(loginBtn)]];UILabel *titleLabel=[[UILabel alloc]init];[titleLabel setTranslatesAutoresizingMaskIntoConstraints:NO];titleLabel.text=@"胖吴货栈发货系统";titleLabel.font=[UIFont systemFontOfSize:14.0];[titleLabel setTextColor:[UIColor colorWithRed:0.992f green:0.318f blue:0.106f alpha:1.00f]];[self.view addSubview:titleLabel];[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"[titleLabel]" options:NSLayoutFormatAlignAllCenterX metrics:nil views:NSDictionaryOfVariableBindings(titleLabel)]];[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[titleLabel]-10-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(titleLabel)]];[self.view addConstraint:[NSLayoutConstraint constraintWithItem:titleLabel attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1 constant:0]];}- (void)didReceiveMemoryWarning {[super didReceiveMemoryWarning];}@end
上面代码中包含了VFL的基本语法,对于更深的语法慢慢的来了解,晒一下做的效果
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前面用的autoLayout自动布局,想着是自动布局Frame会不起作用,一直纠结键盘遮挡的问题。在网上找了下,有网友说改变约束,自己的布局也正好是以顶部的图片依次相对布局 ,所以准备改下顶部的约束就会解决键盘遮挡。自己定了一个标记值,判断键盘隐藏顶部约束值为正,否则为负。可是问题出现了,点击文本框后能键盘弹出后视图能向上,但键盘隐藏之后视图并未回到原位,自己又试着删除全部约束重新添加可还是不行,这个问题让我纠结好久。最后问了下小伙伴oliver,改了下frame问题就解决了。我以为用autolayout并未设置frame,怎么会有呢,问了他下,原来适配也是有frame的。这让我想起了autoLayout的原理,它属于数学的线性规划。最终还是会有一个值的