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：
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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