1.在用UITextView的時候一直很苦惱placeholder的設定，最開始是通過新增label，後來覺得麻煩，就通過UITextView本身的一些特性來進行模擬。

2.UITextView的行間距設定方法網上很容易搜的到，但是運用中卻發現直接設定根本不行，原因是textView一開始必需要有內容（箇中原因，不深究，估計是系統級的），但是有又很奇怪，所以想到個主意，一開始就給textView內容，輸入時刪除，這樣就有了1中的placeholder效果，可謂一舉兩得。

3.做出了placeholder的效果，顏色也需要區別，發現這句：

    _textView.textColor = [UIColor redColor];
 

完全沒有作用，所以也需要通過屬性來設定了，具體的要實現以上內容的程式碼請看下面：

首先要支援UITextViewDelegate；
接著看程式碼：

#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 = @"請在這裡輸入內容";
    _textView.layer.cornerRadius = 10;
    _textView.layer.borderWidth = 1;
    _textView.layer.borderColor
 
 = [UIColor blackColor].CGColor;
    [self.view addSubview:_textView];

    //有內容時該設定才生效，需要切記
    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
{
    //收起鍵盤
    [_textView resignFirstResponder];

}

#pragma mark - UITextViewDelegate

- (BOOL)textViewShouldBeginEditing:(UITextView *)textView
{
    //編輯時刪除代替placeholder效果的內容
    if ([_textView.text isEqualToString:@"請在這裡輸入內容"]) {
        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
{
    //編輯時把placeholder效果顏色變為正常效果
    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
{
    //若編輯結束，內容為空，變最開始placeholder效果
    if ([textView.text isEqualToString:@""]) {
        _textView.text = @"請在這裡輸入內容";
        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

比較容易看懂，就不多解釋了。
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