iOS－UITextView设置行间距，内容颜色（变相设置类似UITextField的placeholder）

来源：互联网发布：对人工智能的看法作文编辑：程序博客网时间：2024/05/29 07:42

1.在用UITextView的时候一直很苦恼placeholder的设置，最开始是通过添加label，后来觉得麻烦，就通过UITextView本身的一些特性来进行模拟。

2.UITextView的行间距设置方法网上很容易搜的到，但是运用中却发现直接设置根本不行，原因是textView一开始必需要有内容（个中原因，不深究，估计是系统级的），但是有又很奇怪，所以想到个主意，一开始就给textView内容，输入时删除，这样就有了1中的placeholder效果，可谓一举两得。

3.做出了placeholder的效果，颜色也需要区别，发现这句：

    _textView.textColor = [UIColor redColor];

完全没有作用，所以也需要通过属性来设置了，具体的要实现以上内容的代码请看下面：
这里写图片描述
首先要支持UITextViewDelegate；
接着看代码：

#import "ViewController.h"@interface ViewController ()<UITextViewDelegate>{    UITextView *_textView;}@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    self.automaticallyAdjustsScrollViewInsets = NO;    _textView = [[UITextView alloc]initWithFrame:CGRectMake(10, 100, 300, 80)];    _textView.delegate = self;    _textView.text = @"请在这里输入内容";    _textView.layer.cornerRadius = 10;    _textView.layer.borderWidth = 1;    _textView.layer.borderColor = [UIColor blackColor].CGColor;    [self.view addSubview:_textView];    //有内容时该设置才生效，需要切记    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];    paragraphStyle.lineSpacing = 8;    NSDictionary *attributes = @{NSFontAttributeName:[UIFont systemFontOfSize:15],NSParagraphStyleAttributeName:paragraphStyle,NSForegroundColorAttributeName:[UIColor grayColor]};    _textView.attributedText = [[NSAttributedString alloc]initWithString:_textView.text attributes:attributes];}- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    //收起键盘    [_textView resignFirstResponder];}#pragma mark - UITextViewDelegate- (BOOL)textViewShouldBeginEditing:(UITextView *)textView{    //编辑时删除代替placeholder效果的内容    if ([_textView.text isEqualToString:@"请在这里输入内容"]) {        textView.text = @"";        NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];        paragraphStyle.lineSpacing = 8;        NSDictionary *attributes = @{NSFontAttributeName:[UIFont systemFontOfSize:15],NSParagraphStyleAttributeName:paragraphStyle,NSForegroundColorAttributeName:[UIColor blackColor]};        _textView.attributedText = [[NSAttributedString alloc]initWithString:_textView.text attributes:attributes];    }    return YES;}- (void)textViewDidChange:(UITextView *)textView{    //编辑时把placeholder效果颜色变为正常效果    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];    paragraphStyle.lineSpacing = 8;    NSDictionary *attributes = @{NSFontAttributeName:[UIFont systemFontOfSize:15],NSParagraphStyleAttributeName:paragraphStyle,NSForegroundColorAttributeName:[UIColor blackColor]};    _textView.attributedText = [[NSAttributedString alloc]initWithString:_textView.text attributes:attributes];}- (void)textViewDidEndEditing:(UITextView *)textView{    //若编辑结束，内容为空，变最开始placeholder效果    if ([textView.text isEqualToString:@""]) {        _textView.text = @"请在这里输入内容";        NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc]init];        paragraphStyle.lineSpacing = 8;        NSDictionary *attributes = @{NSFontAttributeName:[UIFont systemFontOfSize:15],NSParagraphStyleAttributeName:paragraphStyle,NSForegroundColorAttributeName:[UIColor grayColor]};        _textView.attributedText = [[NSAttributedString alloc]initWithString:_textView.text attributes:attributes];    }}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end

比较容易看懂，就不多解释了。
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